/* PEMDAS Pathway CSS - World Class Design */
/* Import main CSS file with all component styles */
@import url('./main.css');

/* Import page-specific styles */
@import url('./pages/privacy-controls.css');
@import url('./pages/quick-start-focus.css');
@import url('./pages/onboarding.css');
@import url('./pages/blog.css');

/* Import celebration animations */
@import url('./components/celebrations.css');

/* Import error states */
@import url('./components/error-states.css');

/* Import skeleton loaders */
@import url('./components/skeleton-loaders.css');

/* Import enhanced feedback */
@import url('./components/feedback-enhanced.css');

/* Import onboarding enhancements */
@import url('./components/onboarding-enhanced.css');

/* Import accessibility enhancements */
@import url('./components/accessibility.css');

/* Import mobile UX enhancements */
@import url('./components/mobile-ux.css');

/* Import unified settings */
@import url('./components/unified-settings.css');

/* Import mobile and styling improvements - MUST LOAD LAST */
@import url('./fixes/mobile-menu-improvements.css');
@import url('./fixes/button-text-improvements.css');
@import url('./fixes/text-readability-enhancements.css');

/* Navigation dropdown UX improvements - MUST LOAD AFTER OTHER FIXES */
@import url('./fixes/nav-dropdown-ux-improvements.css');

/* Navigation text overflow protection */
@import url('./fixes/nav-text-overflow-fix.css');

/* Mobile layout optimizations - FINAL OVERRIDES */
@import url('./fixes/mobile-layout-optimizations.css');

/* Enhanced UX improvements - December 2025 */
@import url('./fixes/enhanced-ux-improvements.css');

/* Comprehensive Design Improvements - January 2025 */
@import url('./design-improvements.css');

/* Quick Start overrides - MUST LOAD LAST */
@import url('./fixes/quick-start-overrides.css');

/* Mobile & Responsive Optimizations - FINAL OVERRIDES */
@import url('./responsive/mobile-optimizations.css');

/* User Experience Fixes - January 2025 */
@import url('./fixes/mobile-keyboard-fix.css');
@import url('./components/settings.css');
@import url('./components/progress-insights.css');
@import url('./components/social-proof.css');

/* ========================================
   WORLD-CLASS UI/UX ENHANCEMENTS
   ======================================== */

/* Core Enhancements - Load First */
@import url('./enhancements/landing-demo-enhanced.css');
@import url('./enhancements/onboarding-enhanced.css');
@import url('./enhancements/progress-visualization.css');
@import url('./enhancements/celebrations-enhanced.css');
@import url('./enhancements/smart-feedback.css');
@import url('./enhancements/mobile-gestures.css');

/* Adaptive Learning System */
@import url('./adaptive-learning.css');

/* Enhanced Visual Feedback & Celebrations */
@import url('./visual-feedback.css');

/* Learning Preferences Panel */
@import url('./learning-preferences.css');

/* Mobile Gestures & Touch Optimization */
@import url('./mobile-gestures.css');

/* Accessibility Enhancements */
@import url('./accessibility-enhancements.css');

/* Interactive Problem Types */
@import url('./interactive-problems.css');

/* Achievement & Gamification System */
@import url('./achievement-system.css');

/* Analytics Dashboard */
@import url('./analytics-dashboard.css');

/* CSS Custom Properties - Essential Variables */

:root {
    /* Primary Brand Colors */
    --primary-color: #667eea;
    --primary-dark: #5a67d8;
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    
    /* Gray Scale */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Semantic Colors */
    --success-color: #22c55e;
    --success-50: #f0fdf4;
    --success-100: #dcfce7;
    --success-200: #bbf7d0;
    --success-300: #86efac;
    --success-400: #4ade80;
    --success-500: #22c55e;
    --success-600: #16a34a;
    --success-700: #15803d;
    
    --error-color: #ef4444;
    --error-50: #fef2f2;
    --error-100: #fee2e2;
    --error-200: #fecaca;
    --error-300: #fca5a5;
    --error-400: #f87171;
    --error-500: #ef4444;
    --error-600: #dc2626;
    --error-700: #b91c1c;
    
    --warning-color: #f59e0b;
    --warning-50: #fffbeb;
    --warning-100: #fef3c7;
    --warning-200: #fde68a;
    --warning-300: #fcd34d;
    --warning-400: #fbbf24;
    --warning-500: #f59e0b;
    --warning-600: #d97706;
    --warning-700: #b45309;
    
    /* Spacing System */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.125rem;
    --radius-base: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.06);
    
    /* Transitions */
    --transition-base: all 0.2s ease-in-out;
    --transition-fast: all 0.1s ease-in-out;
    --transition-slow: all 0.3s ease-in-out;
    
    /* Typography */
    --font-family-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-family-mono: "SF Mono", Monaco, Inconsolata, "Roboto Mono", Consolas, "Courier New", monospace;
    --font-family-base: var(--font-family-sans);
    
    /* Additional Error Colors */
    --error-border: var(--error-500);
    --error-light: var(--error-100);
    
    /* Focus Ring */
    --input-focus-ring: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

/* Reset and base styles */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    /* Performance optimizations */
    -webkit-overflow-scrolling: touch;
    text-rendering: optimizeLegibility;
}

/* Performance optimizations for animations */
.btn,
.module-card,
.stat,
.answer-input,
.btn-true,
.btn-false,
.btn-comparison {
    will-change: transform;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

/* Smooth transitions for all interactive elements */
* {
    -webkit-tap-highlight-color: transparent;
}

/* Better scrolling on mobile */
body {
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;
}

body {
    font-family: var(--font-family-base);
    line-height: 1.6;
    color: var(--gray-800);
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

/* Disable animations when preference is set */
body.no-animations * {
    animation-duration: 0s !important;
    transition-duration: 0s !important;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    font-feature-settings: 'kern' 1, 'liga' 1;
    text-rendering: optimizeLegibility;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-6);
    width: 100%;
}

@media (min-width: 640px) {
    .container {
        padding: 0 var(--space-8);
    }
}

/* Header */
.header {
    /* Fallback for browsers without CSS custom properties */
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background: var(--primary-gradient);
    color: white;
    padding: var(--space-4) 0;
    box-shadow: var(--shadow-lg);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    position: relative;
    z-index: var(--z-sticky);
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.95) 0%, rgba(118, 75, 162, 0.95) 100%);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    z-index: -1;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    color: white;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.025em;
    transition: var(--transition-base);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.logo a:hover {
    transform: translateY(-1px);
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.logo a::before {
    content: '📐';
    font-size: 1.25rem;
    /* Fallback for browsers without filter support */
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.nav {
    display: flex;
    gap: 1rem;
}

.nav-link {
    color: white;
    text-decoration: none;
    padding: var(--space-3) var(--space-5);
    border-radius: var(--radius-lg);
    transition: var(--transition-base);
    font-weight: 500;
    position: relative;
    overflow: hidden;
    border: 1px solid transparent;
    min-height: 44px;
    display: flex;
    align-items: center;
}

.nav-link.active {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.3);
}

.nav-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition-slow);
}

.nav-link:hover {
    background-color: rgba(255, 255, 255, 0.15);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.nav-link:hover::before {
    left: 100%;
}

.nav-link:active {
    transform: translateY(0);
}

/* Main content */
.main {
    flex: 1;
    padding: 2rem 0;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition-base);
    text-align: center;
    position: relative;
    overflow: hidden;
    white-space: nowrap;
    user-select: none;
    -webkit-user-select: none;
    font-family: inherit;
    line-height: 1.5;
    min-height: 44px; /* Accessibility: minimum touch target */
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition-slow);
}

.btn:hover::before {
    left: 100%;
}

.btn:focus {
    /* Fallback for browsers without CSS custom properties */
    outline: 2px solid #667eea;
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.btn:active {
    transform: translateY(1px);
}

.btn-primary {
    /* Fallback for browsers without CSS custom properties */
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background: var(--primary-gradient);
    color: white;
    /* Fallback shadow */
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
    filter: brightness(1.05);
}

.btn-primary:active {
    transform: translateY(0);
    box-shadow: var(--shadow-md);
}

.btn-primary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: var(--shadow-sm);
    filter: none;
}

/* Loading state */
.btn.loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}

.btn.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 16px;
    height: 16px;
    border: 2px solid transparent;
    border-top: 2px solid currentColor;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.btn.loading.btn-primary::after {
    border-top-color: white;
}

@keyframes spin {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}

/* Success state */
.btn.success {
    background: var(--success-color) !important;
    animation: successBounce 0.6s ease-out;
}

@keyframes successBounce {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes selectedPulse {
    0%, 100% { 
        box-shadow: 0 12px 24px rgba(102, 126, 234, 0.4);
    }
    50% { 
        box-shadow: 0 16px 32px rgba(102, 126, 234, 0.6);
        transform: translateY(-6px) scale(1.03);
    }
}

@keyframes checkmarkAppear {
    0% { 
        opacity: 0;
        transform: scale(0) rotate(180deg);
    }
    100% { 
        opacity: 1;
        transform: scale(1) rotate(0deg);
    }
}

.btn-primary:disabled:hover {
    transform: none;
    box-shadow: var(--shadow-sm);
}

.btn-secondary {
    background: linear-gradient(135deg, var(--gray-600) 0%, var(--gray-700) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-secondary:hover {
    background: linear-gradient(135deg, var(--gray-700) 0%, var(--gray-800) 100%);
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

.btn-outline {
    background-color: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    box-shadow: var(--shadow-sm);
}

.btn-outline:hover {
    background: var(--primary-gradient);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

.btn-outline:active {
    transform: translateY(0);
    box-shadow: var(--shadow-md);
}

/* Forms */
.form-group {
    margin-bottom: var(--space-6);
}

.form-group label {
    display: block;
    margin-bottom: var(--space-2);
    font-weight: 600;
    color: var(--gray-700);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.form-input {
    width: 100%;
    padding: var(--space-4);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    transition: var(--transition-base);
    background-color: white;
    box-shadow: var(--shadow-sm);
    font-family: inherit;
    line-height: 1.5;
    min-height: 48px; /* Better touch target for mobile */
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1), var(--shadow-md);
    transform: translateY(-1px);
}

.form-input:hover {
    border-color: var(--gray-300);
}

.form-input::placeholder {
    color: var(--gray-600);
    opacity: 1;
}

/* Login page */
.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 60vh;
    padding: var(--space-8);
}

.login-card {
    background: white;
    padding: var(--space-10);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    max-width: 400px;
    width: 100%;
    position: relative;
    overflow: hidden;
}

.login-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.login-card::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.03) 0%, transparent 70%);
    z-index: -1;
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(10px, -10px) rotate(1deg); }
    66% { transform: translate(-5px, 5px) rotate(-1deg); }
}

.login-card h2 {
    text-align: center;
    margin-bottom: var(--space-2);
    color: var(--gray-800);
    font-weight: 700;
    font-size: 1.875rem;
    letter-spacing: -0.025em;
}

.subtitle {
    text-align: center;
    color: var(--gray-800);
    margin-bottom: var(--space-8);
    font-size: 1.125rem;
    line-height: 1.6;
}

.error-message {
    background-color: var(--error-light);
    color: var(--error-color);
    padding: 0.75rem;
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
    border: 1px solid var(--error-border);
}

.info-box {
    margin-top: 2rem;
    padding: 1rem;
    background-color: #f8f9fa;
    border-radius: 6px;
}

.info-box h3 {
    margin-bottom: 0.5rem;
    color: var(--gray-800);
}

.info-box ul {
    list-style: none;
    padding-left: 0;
}

.info-box li {
    padding: 0.25rem 0;
    color: var(--gray-700);
}

.info-box li:before {
    content: "✓ ";
    color: #28a745;
    font-weight: bold;
}

/* Practice interface */
.practice-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

.user-info {
    background: white;
    padding: var(--space-8);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-xl);
    margin-bottom: var(--space-8);
    position: relative;
    overflow: hidden;
}

.user-info::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.user-info::after {
    content: '';
    position: absolute;
    top: -2px;
    right: -2px;
    width: 100px;
    height: 100px;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.1) 0%, transparent 70%);
    border-radius: 50%;
    z-index: -1;
}

.user-info h2 {
    margin-bottom: 1rem;
    color: #333;
}

.stats-bar {
    display: flex;
    gap: var(--space-8);
    justify-content: center;
    flex-wrap: wrap;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    background: var(--gray-50);
    padding: var(--space-4) var(--space-6);
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    min-width: 120px;
    transition: var(--transition-base);
}

.stat:hover {
    background: white;
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    border-color: var(--primary-color);
}

.stat:hover .stat-value {
    transform: scale(1.05);
    transition: transform var(--transition-fast);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--gray-700);
    margin-bottom: var(--space-1);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
}

/* Module selection */
.module-selection {
    margin-bottom: var(--space-12);
}

.module-header {
    text-align: center;
    margin-bottom: var(--space-8);
}

.module-selection h3 {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--space-6);
    position: relative;
}

.module-selection h3::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--primary-gradient);
    border-radius: var(--radius-full);
}

.continue-learning {
    margin-bottom: var(--space-6);
}

.btn-large {
    padding: var(--space-4) var(--space-8);
    font-size: 1.125rem;
    font-weight: 600;
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-3);
    position: relative;
    overflow: hidden;
}

.btn-large small {
    display: block;
    font-size: 0.875rem;
    font-weight: 400;
    opacity: 0.8;
    margin-top: var(--space-1);
}

.btn-icon {
    font-size: 1.25rem;
}

.module-grid {
    /* Flexbox fallback for older browsers */
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    /* CSS Grid for modern browsers */
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.module-card {
    background: white;
    padding: var(--space-8);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    transition: var(--transition-base);
    border: 2px solid var(--gray-100);
    position: relative;
    overflow: hidden;
}

.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(102, 126, 234, 0.05), transparent);
    transition: var(--transition-slow);
}

.module-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-2xl);
    border-color: var(--gray-200);
}

.module-card:hover::before {
    left: 100%;
}

.module-card.unlocked {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, white 0%, rgba(102, 126, 234, 0.02) 100%);
}

.module-card.unlocked:hover {
    border-color: var(--primary-dark);
    box-shadow: 0 20px 40px rgba(102, 126, 234, 0.15);
}

.module-card.unlocked::after {
    content: '✨';
    position: absolute;
    top: var(--space-4);
    right: var(--space-4);
    font-size: 1.25rem;
    opacity: 0.7;
}

.module-card h4 {
    margin-bottom: 0.5rem;
    color: #333;
}

.module-card p {
    color: var(--gray-700);
    margin-bottom: 1rem;
    font-size: 1rem;
    line-height: 1.5;
}

/* Locked module styles */
.module-card:not(.unlocked) {
    opacity: 0.8;
    cursor: not-allowed;
    position: relative;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

.module-card:not(.unlocked) h4 {
    color: var(--gray-800);
}

.module-card:not(.unlocked) p {
    color: var(--gray-700);
}

.module-card:not(.unlocked):hover {
    transform: none;
    box-shadow: var(--shadow-lg);
    border-color: var(--gray-100);
}

/* Unlock hint styling */
.unlock-hint {
    font-size: 0.875rem;
    color: var(--gray-800);
    margin-top: 4px;
    font-style: italic;
    line-height: 1.4;
}

/* Near-mastery indicators */
.near-mastery {
    color: var(--warning-color);
    font-weight: 600;
    display: block;
    margin-top: 4px;
}

.good-progress {
    color: var(--success-color);
    font-weight: 500;
    display: block;
    margin-top: 4px;
}

/* Locked module tooltip */
.locked-module-tooltip {
    background: var(--gray-800);
    color: white;
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    box-shadow: var(--shadow-xl);
    max-width: 250px;
    animation: fadeInUp 0.2s ease-out;
}

.locked-module-tooltip .tooltip-content strong {
    display: block;
    margin-bottom: var(--space-1);
}

.locked-module-tooltip .tooltip-content p {
    margin: 0;
    opacity: 0.9;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateX(-50%) translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
}

.progress-bar {
    width: 100%;
    height: 10px;
    background-color: var(--gray-200);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--space-3);
    box-shadow: var(--shadow-inner);
}

.progress-fill {
    height: 100%;
    background: var(--primary-gradient);
    transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent 0%, rgba(255, 255, 255, 0.3) 50%, transparent 100%);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.module-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.875rem;
}

.locked {
    color: var(--gray-800);
}

/* Problem area */
.problem-area {
    background: white;
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    overflow: hidden;
    border: 1px solid var(--gray-100);
}

.problem-header {
    background: var(--primary-gradient);
    color: white;
    padding: var(--space-6) var(--space-8);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
}

.problem-header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
}

.problem-info {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    font-weight: 500;
}

.problem-timer {
    background: rgba(255,255,255,0.15);
    padding: var(--space-2) var(--space-4);
    border-radius: var(--radius-full);
    font-family: var(--font-family-mono);
    font-weight: 600;
    font-size: 0.875rem;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}

/* Breadcrumb navigation */
.breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-bottom: var(--space-6);
    padding: var(--space-3) var(--space-6);
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--gray-100);
}

.breadcrumb-item {
    color: var(--gray-700);
    font-size: 0.875rem;
    font-weight: 500;
}

.breadcrumb-item.active {
    color: var(--primary-color);
    font-weight: 600;
}

.breadcrumb-separator {
    color: var(--gray-700);
    font-size: 0.75rem;
}

/* Progress indicators */
.progress-indicator {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-bottom: var(--space-4);
    padding: var(--space-3);
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}

.progress-step {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transition: var(--transition-base);
}

.progress-step.completed {
    background: rgba(255, 255, 255, 0.8);
    transform: scale(1.2);
}

.progress-step.current {
    background: white;
    transform: scale(1.4);
    box-shadow: 0 0 0 2px rgba(255, 255, 255, 0.3);
}

.review-badge, .scaffolding-badge {
    background-color: rgba(255,255,255,0.2);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
}

.problem-timer {
    font-family: 'Courier New', monospace;
    font-size: 1.1rem;
    font-weight: bold;
}

.problem-card {
    padding: var(--space-12) var(--space-8);
    background: linear-gradient(135deg, #fafbff 0%, #f8fafc 100%);
    position: relative;
}

.problem-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--primary-gradient);
    border-radius: 0 0 var(--radius-full) var(--radius-full);
}

.problem-prompt {
    /* Fallback for browsers without clamp() support */
    font-size: 1.5rem;
    font-size: clamp(1.25rem, 3vw, 1.75rem);
    text-align: center;
    margin-bottom: var(--space-10);
    color: var(--gray-800);
    font-weight: 500;
    line-height: 1.4;
    min-height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    word-wrap: break-word;
    padding: var(--space-6);
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--gray-100);
}

.answer-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    justify-content: center;
    align-items: center;
    margin-bottom: 2rem;
}

.input-section {
    display: flex;
    gap: 1rem;
    justify-content: center;
    align-items: center;
}

.answer-input {
    font-size: 1.25rem;
    padding: var(--space-4) var(--space-6);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    text-align: center;
    min-width: 200px;
    min-height: 52px; /* Larger touch target for primary input */
    transition: var(--transition-base);
    background: white;
    box-shadow: var(--shadow-sm);
}

.answer-input:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1), var(--shadow-lg);
    transform: translateY(-1px);
}

.answer-input:hover {
    border-color: var(--gray-300);
    box-shadow: var(--shadow-md);
}

/* Input success state */
.answer-input.success {
    border-color: var(--success-color);
    background: var(--success-light);
    animation: successPulse 0.6s ease-out;
}

/* Input error state */
.answer-input.error {
    border-color: var(--error-color);
    background: var(--error-light);
    animation: errorShake 0.6s ease-out;
}

@keyframes successPulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.02); }
    100% { transform: scale(1); }
}

@keyframes errorShake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-4px); }
    75% { transform: translateX(4px); }
}

/* True/False button interface */
.true-false-buttons, .comparison-buttons {
    flex-direction: column;
    gap: 1.5rem;
}

.true-false-prompt, .comparison-prompt {
    font-size: 1.1rem;
    color: var(--gray-800);
    text-align: center;
    margin-bottom: 0.5rem;
}

.button-group {
    display: flex;
    gap: 2rem;
    justify-content: center;
}

.btn-true, .btn-false, .btn-comparison {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-8) var(--space-10);
    border: 3px solid transparent;
    border-radius: var(--radius-2xl);
    font-size: 1.125rem;
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition-base);
    min-width: 160px;
    min-height: 80px; /* Better touch target */
    background: white;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
    user-select: none;
    -webkit-user-select: none;
}

.btn-true::before, .btn-false::before, .btn-comparison::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: var(--transition-slow);
}

.btn-true:hover::before, .btn-false:hover::before, .btn-comparison:hover::before {
    left: 100%;
}

.btn-true {
    color: var(--success-color);
    border-color: var(--success-color);
}

.btn-true:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--success-color) 0%, #059669 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(16, 185, 129, 0.3);
    border-color: var(--success-color);
}

.btn-true:active:not(:disabled) {
    transform: translateY(-2px) scale(1.01);
    box-shadow: 0 8px 16px rgba(16, 185, 129, 0.2);
}

.btn-false {
    color: var(--error-color);
    border-color: var(--error-color);
}

.btn-false:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--error-color) 0%, #dc2626 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(239, 68, 68, 0.3);
    border-color: var(--error-color);
}

.btn-false:active:not(:disabled) {
    transform: translateY(-2px) scale(1.01);
    box-shadow: 0 8px 16px rgba(239, 68, 68, 0.2);
}

.btn-true.selected {
    background: linear-gradient(135deg, var(--success-color) 0%, #059669 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(16, 185, 129, 0.4);
    border-color: var(--success-color);
    animation: selectedPulse 1.5s ease-in-out infinite;
}

.btn-true.selected::after {
    content: '✓';
    position: absolute;
    top: 8px;
    right: 8px;
    font-size: 1.25rem;
    animation: checkmarkAppear 0.3s ease-out;
}

.btn-false.selected {
    background: linear-gradient(135deg, var(--error-color) 0%, #dc2626 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(239, 68, 68, 0.4);
    border-color: var(--error-color);
    animation: selectedPulse 1.5s ease-in-out infinite;
}

.btn-false.selected::after {
    content: '✗';
    position: absolute;
    top: 8px;
    right: 8px;
    font-size: 1.25rem;
    animation: checkmarkAppear 0.3s ease-out;
    animation: pulse-error 2s infinite;
}

@keyframes pulse-success {
    0%, 100% { box-shadow: 0 12px 24px rgba(16, 185, 129, 0.4); }
    50% { box-shadow: 0 16px 32px rgba(16, 185, 129, 0.6); }
}

@keyframes pulse-error {
    0%, 100% { box-shadow: 0 12px 24px rgba(239, 68, 68, 0.4); }
    50% { box-shadow: 0 16px 32px rgba(239, 68, 68, 0.6); }
}

.btn-true:disabled, .btn-false:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.thumb-icon {
    font-size: 2.5rem;
    line-height: 1;
    /* Fallback for browsers without filter support */
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
    transition: var(--transition-base);
}

.btn-true:hover .thumb-icon, .btn-false:hover .thumb-icon {
    transform: scale(1.1);
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.2));
}

.btn-text {
    font-size: 1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Comparison button styles */
.btn-comparison {
    color: #8b5cf6;
    border-color: #8b5cf6;
}

.btn-comparison:hover:not(:disabled) {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(139, 92, 246, 0.3);
    border-color: #8b5cf6;
}

.btn-comparison:active:not(:disabled) {
    transform: translateY(-2px) scale(1.01);
    box-shadow: 0 8px 16px rgba(139, 92, 246, 0.2);
}

.btn-comparison.selected {
    background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%);
    color: white;
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 24px rgba(139, 92, 246, 0.4);
    border-color: #8b5cf6;
    animation: pulse-comparison 2s infinite;
}

@keyframes pulse-comparison {
    0%, 100% { box-shadow: 0 12px 24px rgba(139, 92, 246, 0.4); }
    50% { box-shadow: 0 16px 32px rgba(139, 92, 246, 0.6); }
}

.btn-comparison:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.comparison-icon {
    font-size: 3rem;
    line-height: 1;
    font-weight: bold;
    font-family: var(--font-family-mono);
    /* Fallback for browsers without filter support */
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
    transition: var(--transition-base);
}

.btn-comparison:hover .comparison-icon {
    transform: scale(1.1);
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.2));
}

.feedback-area {
    text-align: center;
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.feedback-message {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.feedback-area.correct {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.feedback-area.incorrect {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.feedback-area.error {
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.correct-answer {
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.error-explanation {
    font-size: 0.875rem;
    color: var(--gray-700);
    font-style: italic;
}

.hint-steps {
    background-color: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 6px;
    padding: 1rem;
    margin-top: 1rem;
}

.hint-steps h4 {
    margin-bottom: 0.5rem;
    color: #856404;
}

.hint-steps ul {
    list-style: none;
    padding-left: 0;
}

.hint-steps li {
    padding: 0.25rem 0;
    color: #856404;
}

.problem-actions {
    padding: 1rem 2rem;
    display: flex;
    justify-content: center;
    gap: 1rem;
    background-color: #f8f9fa;
}

/* Progress page */
.progress-container {
    max-width: 1000px;
    margin: 0 auto;
}

.progress-header {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.progress-header h2 {
    margin-bottom: 1rem;
    color: #333;
}

.overall-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.stat-card {
    text-align: center;
    padding: 1rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border-radius: 8px;
}

.stat-card h3 {
    font-size: 2rem;
    margin-bottom: 0.25rem;
}

.stat-card p {
    font-size: 0.875rem;
    opacity: 0.9;
}

.modules-progress {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-bottom: 2rem;
}

.module-progress-card {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    overflow: hidden;
}

.module-header {
    padding: 1.5rem;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border-bottom: 1px solid #dee2e6;
}

.module-header h3 {
    margin-bottom: 0.5rem;
    color: #333;
}

.module-header p {
    color: var(--gray-700);
    margin-bottom: 1rem;
}

.module-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

.mastered-count {
    font-weight: 500;
    color: var(--gray-800);
}

.overall-progress-bar {
    flex: 1;
    height: 10px;
    background-color: #e9ecef;
    border-radius: 5px;
    overflow: hidden;
}

.tiers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    padding: 1.5rem;
}

.tier-card {
    padding: 1rem;
    border-radius: 8px;
    border: 2px solid #e9ecef;
    transition: all 0.2s;
}

.tier-card.mastered {
    border-color: #28a745;
    background-color: #f8fff9;
}

.tier-card.unlocked {
    border-color: #667eea;
    background-color: #f8f9ff;
}

.tier-card.locked {
    border-color: #dee2e6;
    background-color: #f8f9fa;
    opacity: 0.7;
}

.tier-card h4 {
    margin-bottom: 0.5rem;
    color: #333;
    font-size: 0.875rem;
}

.status-badge {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 500;
}

.status-badge.mastered {
    background-color: #d4edda;
    color: #155724;
}

.status-badge.unlocked {
    background-color: #cce7ff;
    color: #004085;
}

.status-badge.locked {
    background-color: #e2e3e5;
    color: var(--gray-700);
}

.mastery-progress {
    margin-top: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.mastery-bar {
    flex: 1;
    height: 6px;
    background-color: #e9ecef;
    border-radius: 3px;
    overflow: hidden;
}

.mastery-fill {
    height: 100%;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    transition: width 0.3s ease;
}

.mastery-score {
    font-size: 0.875rem;
    color: var(--gray-700);
    font-weight: 500;
    line-height: 1.4;
}

.detailed-stats {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.detailed-stats h3 {
    margin-bottom: 1.5rem;
    color: #333;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.stat-section h4 {
    margin-bottom: 1rem;
    color: var(--gray-800);
}

.actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

/* Achievement notification */
.achievement-notification {
    position: fixed;
    top: var(--space-6);
    right: var(--space-6);
    background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
    color: var(--gray-800);
    padding: var(--space-6);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    z-index: var(--z-toast);
    animation: slideInRight 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid rgba(251, 191, 36, 0.3);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    max-width: 320px;
}

.achievement-close {
    position: absolute;
    top: 8px;
    right: 12px;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: #92400e;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.achievement-close:hover {
    opacity: 1;
}

@keyframes slideInRight {
    from {
        transform: translateX(100%) scale(0.8);
        opacity: 0;
    }
    to {
        transform: translateX(0) scale(1);
        opacity: 1;
    }
}

@keyframes slideOutRight {
    from {
        transform: translateX(0) scale(1);
        opacity: 1;
    }
    to {
        transform: translateX(100%) scale(0.8);
        opacity: 0;
    }
}

/* Additional utility animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes scaleIn {
    from { transform: scale(0.9); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

/* Utility classes for animations */
.animate-fade-in {
    animation: fadeIn 0.3s ease-out;
}

.animate-scale-in {
    animation: scaleIn 0.2s ease-out;
}

.achievement-content {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.achievement-icon {
    font-size: 2rem;
}

.achievement-text h4 {
    margin-bottom: 0.25rem;
    font-size: 1rem;
}

.achievement-text p {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* Footer */
.footer {
    background: linear-gradient(135deg, var(--gray-800) 0%, var(--gray-900) 100%);
    color: white;
    padding: var(--space-12) 0;
    margin-top: auto;
    position: relative;
    overflow: hidden;
}

.footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
}

.footer::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.05) 0%, transparent 70%);
    z-index: -1;
    animation: float 8s ease-in-out infinite;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-link {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition-base);
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    position: relative;
    overflow: hidden;
}

.footer-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: var(--transition-slow);
}

.footer-link:hover {
    color: white;
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateY(-1px);
}

.footer-link:hover::before {
    left: 100%;
}

.footer-badges {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.badge {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0.05) 100%);
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    white-space: nowrap;
    font-weight: 600;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--space-1);
}

.badge:hover {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.2) 0%, rgba(255, 255, 255, 0.1) 100%);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* Privacy, Security, and About Pages */
.privacy-container, .security-container, .about-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.privacy-header, .security-header, .about-header {
    text-align: center;
    margin-bottom: 3rem;
}

.privacy-header h1, .security-header h1, .about-header h1 {
    color: #333;
    margin-bottom: 0.5rem;
}

.last-updated, .security-subtitle, .about-subtitle {
    color: var(--gray-700);
    font-style: italic;
    margin-bottom: 1rem;
}

.privacy-badges, .security-badges {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.privacy-badge, .security-badge {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.privacy-section, .security-section, .about-section {
    margin-bottom: 3rem;
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.privacy-section h2, .security-section h2, .about-section h2 {
    color: #333;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid #667eea;
    padding-bottom: 0.5rem;
}

.privacy-section h3, .security-section h3, .about-section h3 {
    color: var(--gray-800);
    margin-bottom: 1rem;
    margin-top: 1.5rem;
}

.promise-grid, .security-grid, .features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.promise-item, .security-item, .feature-item {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid #667eea;
}

.promise-item h3, .security-item h3, .feature-item h3 {
    color: #667eea;
    margin-bottom: 0.5rem;
    margin-top: 0;
}

.curriculum-path {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.curriculum-item {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem;
    border-radius: 8px;
    text-align: center;
    font-weight: 500;
}

.promises-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.promise {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid #28a745;
}

.promise h4 {
    color: #28a745;
    margin-bottom: 0.5rem;
    margin-top: 0;
}

.contact-methods {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.contact-method {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid #17a2b8;
}

.contact-method h4 {
    color: #17a2b8;
    margin-bottom: 0.5rem;
    margin-top: 0;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.btn-outline {
    background: transparent;
    border: 2px solid white;
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    transition: all 0.2s;
}

.btn-outline:hover {
    background: white;
    color: #667eea;
}

.privacy-summary, .security-summary, .about-summary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    margin-top: 3rem;
}

.privacy-summary h2, .security-summary h2, .about-summary h2 {
    color: white;
    border-bottom: 2px solid rgba(255,255,255,0.3);
    margin-bottom: 1rem;
}

/* Typography Enhancements */
body {
    line-height: 1.6;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

h1, h2, h3, h4, h5, h6 {
    line-height: 1.3;
    font-weight: 600;
}

p {
    margin-bottom: 1rem;
}

ul, ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.25rem;
}

/* Print Styles */
@media print {
    .navbar, .footer, .btn, .header {
        display: none !important;
    }
    
    .privacy-container, .security-container, .about-container {
        max-width: none;
        padding: 0;
    }
    
    .privacy-section, .security-section, .about-section {
        box-shadow: none;
        border: 1px solid #ddd;
        page-break-inside: avoid;
    }
    
    /* Print-friendly colors */
    * {
        background: white !important;
        color: black !important;
        text-shadow: none !important;
        box-shadow: none !important;
    }
    
    .module-card, .feature-card {
        border: 1px solid #ccc !important;
        page-break-inside: avoid;
    }
    
    /* Ensure text is readable */
    body {
        font-size: 12pt;
        line-height: 1.4;
    }
    
    h1, h2, h3, h4, h5, h6 {
        page-break-after: avoid;
    }
}

/* Accessibility Enhancements */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles for keyboard navigation */
a:focus, button:focus, input:focus, textarea:focus, select:focus {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --gray-400: #666;
        --gray-500: #555;
        --gray-600: #333;
        --gray-700: #222;
    }
    
    .privacy-section, .security-section, .about-section {
        border: 2px solid #000;
    }
    
    .promise-item, .security-item, .feature-item {
        border: 1px solid #000;
    }
    
    .btn {
        border: 2px solid currentColor;
    }
    
    .module-card {
        border: 2px solid #000;
    }
    
    .feedback-area {
        border: 2px solid currentColor;
    }
}

/* Enhanced focus styles for better accessibility */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.btn:focus,
.module-card:focus,
.nav-link:focus {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
    z-index: 10;
    position: relative;
}

/* Keyboard navigation indicators */
.keyboard-user *:focus {
    outline: 3px solid var(--primary-color);
    outline-offset: 3px;
    box-shadow: 0 0 0 6px rgba(102, 126, 234, 0.2);
}

/* Better focus for interactive elements */
.module-card:focus {
    transform: translateY(-2px);
    box-shadow: var(--shadow-2xl), 0 0 0 3px rgba(102, 126, 234, 0.3);
}

.btn-true:focus,
.btn-false:focus,
.btn-comparison:focus {
    transform: translateY(-2px) scale(1.02);
    box-shadow: var(--shadow-xl), 0 0 0 3px rgba(102, 126, 234, 0.3);
}

/* Focus-visible for modern browsers */
*:focus:not(:focus-visible) {
    outline: none;
}

*:focus-visible {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}

/* Skip link for screen readers */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: #000;
    color: #fff;
    padding: 8px;
    text-decoration: none;
    border-radius: 4px;
    z-index: 1000;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 6px;
}

/* Internet Explorer and older browser support */
@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
    /* IE10+ specific styles */
    .module-grid {
        display: -ms-flexbox;
        -ms-flex-wrap: wrap;
    }
    
    .features-grid, .trust-grid {
        display: -ms-flexbox;
        -ms-flex-wrap: wrap;
    }
    
    /* Remove backdrop-filter for IE */
    .header {
        -webkit-backdrop-filter: none;
        backdrop-filter: none;
    }
}

/* Safari-specific fixes */
@supports (-webkit-appearance: none) {
    .btn {
        -webkit-appearance: none;
    }
    
    input[type="text"],
    input[type="email"],
    input[type="password"] {
        -webkit-appearance: none;
        border-radius: var(--radius-md);
    }
}

/* Firefox-specific fixes */
@-moz-document url-prefix() {
    .btn {
        -moz-appearance: none;
    }
    
    /* Fix for Firefox flexbox gap support */
    .module-grid > * {
        margin-bottom: 1rem;
    }
    
    .features-grid > *,
    .trust-grid > * {
        margin-bottom: 2rem;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Landing Page Styles */
.landing-page {
    min-height: 100vh;
}

/* Hero Section */
.hero-section {
    background: var(--primary-gradient);
    color: white;
    padding: var(--space-20) 0;
    min-height: 85vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(255, 255, 255, 0.05) 0%, transparent 50%);
    z-index: 1;
}

.hero-section::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        conic-gradient(from 0deg, transparent, rgba(255, 255, 255, 0.03), transparent),
        conic-gradient(from 90deg, transparent, rgba(255, 255, 255, 0.02), transparent);
    animation: rotate 20s linear infinite;
    z-index: 0;
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-8);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-16);
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-title {
    /* Fallback for browsers without clamp() support */
    font-size: 3rem;
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    margin-bottom: var(--space-6);
    line-height: 1.1;
    letter-spacing: -0.02em;
    color: white;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    /* Removed gradient text effect for better accessibility */
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    line-height: 1.4;
}

.hero-features {
    display: flex;
    gap: 2rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.feature-highlight {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    background: linear-gradient(135deg, rgba(0, 0, 0, 0.2) 0%, rgba(0, 0, 0, 0.1) 100%);
    padding: var(--space-4) var(--space-6);
    border-radius: var(--radius-xl);
    -webkit-backdrop-filter: blur; backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    transition: var(--transition-base);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}

.feature-highlight:hover {
    transform: translateY(-2px);
    background: linear-gradient(135deg, rgba(0, 0, 0, 0.3) 0%, rgba(0, 0, 0, 0.15) 100%);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.25);
}

.feature-icon {
    font-size: 1.5rem;
    color: white;
}

.feature-text {
    font-weight: 600;
    color: white;
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
}

.hero-cta {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-hero {
    background: white;
    color: #667eea;
    padding: 1rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    display: inline-block;
}

.btn-hero:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.2);
}

.hero-cta .btn-secondary {
    background: transparent;
    color: white;
    padding: 1rem 2rem;
    border: 2px solid white;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    display: inline-block;
}

.hero-cta .btn-secondary:hover {
    background: white;
    color: #667eea;
}

/* Hero Visual Demo */
.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.demo-problem {
    background: white;
    padding: var(--space-10);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    text-align: center;
    max-width: 450px;
    position: relative;
    overflow: hidden;
    border: 1px solid rgba(102, 126, 234, 0.1);
}

.demo-problem::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.demo-problem::after {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.05) 0%, transparent 70%);
    z-index: -1;
    animation: float 4s ease-in-out infinite;
}

.demo-question {
    font-size: 1.5rem;
    color: #333;
    margin-bottom: 2rem;
    font-weight: 600;
}

.demo-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.demo-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 1.5rem;
    border: 3px solid transparent;
    border-radius: 12px;
    background: #f8f9fa;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 100px;
}

.demo-true {
    color: #28a745;
    border-color: #28a745;
}

.demo-false {
    color: #dc3545;
    border-color: #dc3545;
}

.demo-btn.demo-selected {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.2);
}

.demo-true.demo-selected {
    background-color: #28a745;
    color: white;
}

.demo-false.demo-selected {
    background-color: #dc3545;
    color: white;
}

/* Sections */
.features-section, .how-it-works-section, .trust-section {
    padding: 4rem 0;
}

.features-section {
    background: #f8f9fa;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #333;
}

.features-grid, .trust-grid {
    /* Flexbox fallback for older browsers */
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2rem;
    /* CSS Grid for modern browsers */
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.feature-card, .trust-item {
    background: white;
    padding: var(--space-10);
    border-radius: var(--radius-2xl);
    text-align: center;
    box-shadow: var(--shadow-lg);
    transition: var(--transition-base);
    border: 1px solid var(--gray-100);
    position: relative;
    overflow: hidden;
}

.feature-card::before, .trust-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(102, 126, 234, 0.03), transparent);
    transition: var(--transition-slow);
}

.feature-card:hover, .trust-item:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-2xl);
    border-color: var(--gray-200);
}

.feature-card:hover::before, .trust-item:hover::before {
    left: 100%;
}

.feature-icon-large, .trust-icon {
    font-size: 3.5rem;
    margin-bottom: var(--space-6);
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.1));
    transition: var(--transition-base);
}

.feature-card:hover .feature-icon-large,
.trust-item:hover .trust-icon {
    transform: scale(1.1) rotate(5deg);
    filter: drop-shadow(0 8px 16px rgba(0, 0, 0, 0.15));
}

.feature-card h3, .trust-item h3 {
    margin-bottom: 1rem;
    color: #333;
}

.feature-card p, .trust-item p {
    color: var(--gray-700);
    line-height: 1.6;
}

/* How It Works */
.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.step-card {
    text-align: center;
    padding: 2rem;
}

.step-number {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: bold;
    margin: 0 auto 1rem;
}

.step-card h3 {
    margin-bottom: 1rem;
    color: #333;
}

.step-card p {
    color: var(--gray-700);
    line-height: 1.6;
}

/* Signup Section */
.signup-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
}

.signup-card {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
    padding: 0 2rem;
}

.signup-card h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.signup-card p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.signup-form {
    max-width: 400px;
    margin: 0 auto;
}

.input-group {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.signup-input {
    flex: 1;
    padding: 1rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    outline: none;
}

.signup-input:focus {
    box-shadow: 0 0 0 3px rgba(255,255,255,0.3);
}

.btn-signup {
    background: #28a745;
    color: white;
    padding: 1rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}

.btn-signup:hover {
    background: #218838;
    transform: translateY(-1px);
}

.signup-note {
    color: rgba(255,255,255,0.8);
    font-size: 0.9rem;
    margin-top: 1rem;
}

/* Trust Section */
.trust-section {
    background: #f8f9fa;
}

/* Responsive design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .header .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .stats-bar {
        flex-direction: column;
        gap: 1rem;
    }
    
    .module-grid {
        grid-template-columns: 1fr;
    }
    
    .answer-section {
        flex-direction: column;
    }
    
    .input-section {
        flex-direction: column;
        width: 100%;
    }
    
    .answer-input {
        min-width: auto;
        width: 100%;
    }
    
    .button-group {
        flex-direction: column;
        gap: 1rem;
        width: 100%;
    }
    
    .btn-true, .btn-false, .btn-comparison {
        width: 100%;
        max-width: 200px;
        margin: 0 auto;
    }
    
    .problem-actions {
        flex-direction: column;
    }
    
    .overall-stats {
        grid-template-columns: 1fr;
    }
    
    .tiers-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .actions {
        flex-direction: column;
    }
    
    .achievement-notification {
        left: 20px;
        right: 20px;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
    
    .privacy-container, .security-container, .about-container {
        padding: 1rem;
    }
    
    .privacy-section, .security-section, .about-section {
        padding: 1.5rem;
    }
    
    .promise-grid, .security-grid, .features-grid {
        grid-template-columns: 1fr;
    }
    
    .curriculum-path {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn-outline {
        width: 100%;
        max-width: 300px;
    }
    
    /* Landing page mobile styles */
    .hero-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
        padding: 0 1rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-features {
        justify-content: center;
        gap: 1rem;
    }
    
    .feature-highlight {
        flex-direction: column;
        text-align: center;
        padding: 0.5rem;
    }
    
    .hero-cta {
        justify-content: center;
        flex-direction: column;
        align-items: center;
    }
    
    .btn-hero, .hero-cta .btn-secondary {
        width: 100%;
        max-width: 280px;
    }
    
    .demo-problem {
        max-width: 300px;
        padding: 1.5rem;
    }
    
    .demo-question {
        font-size: 1.2rem;
    }
    
    .demo-buttons {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .demo-btn {
        width: 100%;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .features-grid, .steps-grid, .trust-grid {
        grid-template-columns: 1fr;
        padding: 0 1rem;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    .signup-input, .btn-signup {
        width: 100%;
    }
    
    .signup-card h2 {
        font-size: 2rem;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
.btn:focus,
.form-input:focus,
.module-card:focus,
.btn-true:focus,
.btn-false:focus,
.btn-comparison:focus {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .btn-primary {
        background: #000;
        border: 2px solid #fff;
    }
    
    .module-card {
        border: 2px solid #000;
    }
}

/* Privacy Commitment Styles */
.privacy-commitment {
    background: rgba(255, 255, 255, 0.1);
    padding: var(--space-6);
    border-radius: var(--radius-xl);
    margin-top: var(--space-6);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.privacy-commitment h3 {
    color: white;
    margin-bottom: var(--space-4);
    border-bottom: none;
}

/* ========================================
   MOBILE-FIRST DESIGN ENHANCEMENTS
   ======================================== */

/* Enhanced Mobile Breakpoints */
/* Extra small devices (phones, 320px and up) */
/* Extra small screens (phones in portrait) */
@media (max-width: 320px) {
    .container {
        padding: 0 0.5rem;
    }
    
    .header {
        padding: 0.75rem 0;
    }
    
    .logo a {
        font-size: 1.25rem;
    }
    
    .btn {
        padding: 0.5rem 1rem;
        font-size: 0.875rem;
    }
    
    .module-card {
        padding: 1rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}

/* Small screens (phones) */
@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .stats-bar {
        gap: var(--space-4);
        flex-direction: column;
    }
    
    .stat {
        min-width: 100px;
        padding: var(--space-3) var(--space-4);
    }
    
    .module-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
        padding: 0.5rem;
    }
    
    .module-card {
        padding: var(--space-6);
        margin-bottom: 1rem;
    }
    
    .module-card h4 {
        font-size: 1.125rem;
        line-height: 1.4;
    }
    
    .problem-area {
        margin: 0 -1rem;
        border-radius: 0;
    }
    
    .problem-card {
        padding: var(--space-8) var(--space-4);
    }
    
    .button-group {
        flex-direction: column;
        gap: var(--space-4);
    }
    
    .btn-true, .btn-false, .btn-comparison {
        min-width: 100%;
        padding: var(--space-6) var(--space-4);
    }
    }
    
    .problem-card {
        padding: 1.5rem;
        margin-bottom: 1rem;
    }
    
    .btn {
        min-height: 44px;
        font-size: 1rem;
        padding: 0.75rem 1rem;
    }
    
    .stats-bar {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    
    .stat {
        text-align: center;
        padding: 0.75rem;
        background: rgba(255, 255, 255, 0.1);
        border-radius: 0.5rem;
    }
    
    .overall-stats {
        grid-template-columns: 1fr;
        gap: 0.75rem;
    }
    
    .tiers-grid {
        grid-template-columns: 1fr;
        gap: 0.75rem;
    }
    
    .tier-card {
        padding: 1rem;
    }
    
    /* Better tooltip positioning on very small screens */
    .locked-module-tooltip {
        position: fixed;
        left: 1rem !important;
        right: 1rem !important;
        top: auto !important;
        bottom: 1rem !important;
        transform: none !important;
        max-width: none;
        width: auto;
    }
}

/* Small devices (landscape phones, 481px to 640px) */
@media (min-width: 481px) and (max-width: 640px) {
    .module-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
    
    .problem-prompt {
        /* Fallback for browsers without clamp() support */
        font-size: 1.875rem;
        font-size: clamp(1.75rem, 4vw, 2rem);
    }
    
    .btn-true, .btn-false, .btn-comparison {
        min-width: 120px;
    }
}

/* Medium devices (tablets, 641px to 1024px) */
@media (min-width: 641px) and (max-width: 1024px) {
    .module-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 2rem;
    }
    
    .overall-stats {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .tiers-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Enhanced Touch Targets */
@media (max-width: 640px) {
    .btn, .module-card, .answer-input {
        min-height: 44px;
    }
    
    .btn-true, .btn-false, .btn-comparison {
        min-height: 48px;
        padding: 0.875rem 1rem;
        font-size: 1rem;
    }
    
    .answer-input {
        font-size: 1.125rem;
        padding: 1rem;
    }
    
    /* Better spacing for touch interfaces */
    .button-group {
        gap: 1rem;
    }
    
    .problem-actions {
        gap: 1rem;
        padding: 1rem 0;
    }
}

/* Enhanced Accessibility */
@media (max-width: 640px) {
    .btn:focus,
    .module-card:focus,
    .answer-input:focus {
        outline: 3px solid var(--primary-color);
        outline-offset: 2px;
    }
    
    /* Larger tap targets for small screens */
    .nav-link {
        padding: 0.75rem 1rem;
        margin: 0.25rem;
    }
}

/* Dark Mode Enhancements */
@media (prefers-color-scheme: dark) {
    body {
        background: linear-gradient(135deg, #1f2937 0%, #111827 100%);
        color: #f9fafb;
    }
    
    .module-card {
        background: #374151;
        border-color: #4b5563;
        color: #f9fafb;
    }
    
    .module-card h4 {
        color: #f9fafb;
    }
    
    .module-card p {
        color: #d1d5db;
    }
    
    .problem-card {
        background: #374151;
        color: #f9fafb;
    }
    
    .problem-prompt {
        color: #f9fafb;
    }
    
    .answer-input {
        background: #4b5563;
        border-color: #6b7280;
        color: #f9fafb;
    }
    
    .answer-input:focus {
        border-color: var(--primary-color);
        background: #374151;
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    .module-card {
        border: 2px solid;
    }
    
    .module-card p {
        color: var(--gray-900);
        font-weight: var(--font-weight-medium);
    }
    
    .info-box h3 {
        color: var(--gray-900);
        font-weight: var(--font-weight-bold);
    }
    
    .info-box li {
        color: var(--gray-800);
        font-weight: var(--font-weight-medium);
    }
    
    .true-false-prompt, .comparison-prompt {
        color: var(--gray-900);
        font-weight: var(--font-weight-bold);
    }
    
    .error-explanation {
        color: var(--gray-800);
        font-weight: var(--font-weight-medium);
    }
    
    .module-header p {
        color: var(--gray-800);
        font-weight: var(--font-weight-medium);
    }
    
    .mastered-count {
        color: var(--gray-900);
        font-weight: var(--font-weight-bold);
    }
    
    .mastery-score {
        color: var(--gray-800);
        font-weight: var(--font-weight-semibold);
    }
    
    .stat-section h4 {
        color: var(--gray-900);
        font-weight: var(--font-weight-bold);
    }
    
    .last-updated, .security-subtitle, .about-subtitle {
        color: var(--gray-800);
        font-weight: var(--font-weight-medium);
    }
    
    .privacy-section h3, .security-section h3, .about-section h3 {
        color: var(--gray-900);
        font-weight: var(--font-weight-bold);
    }
    
    .feature-card p, .trust-item p, .step-card p {
        color: var(--gray-800);
        font-weight: var(--font-weight-medium);
    }
    
    .btn {
        border: 2px solid;
        font-weight: 700;
    }
    
    .problem-prompt {
        font-weight: 700;
    }
    
    .answer-input {
        border: 2px solid;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .module-card:hover {
        transform: none;
    }
}

/* Print Styles */
@media print {
    .header, .footer, .nav {
        display: none !important;
    }
    
    .problem-area {
        page-break-inside: avoid;
    }
    
    .module-card {
        page-break-inside: avoid;
        box-shadow: none;
        border: 1px solid #000;
    }
}

/* Tutorial Styles */
.tutorial-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn var(--transition-base);
}

.tutorial-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    -webkit-backdrop-filter: blur; backdrop-filter: blur(4px);
}

.tutorial-content {
    position: relative;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-2xl);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow: hidden;
    animation: slideInUp var(--transition-base);
}

.tutorial-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-6);
    border-bottom: 1px solid var(--gray-200);
    background: var(--primary-gradient);
    color: white;
}

.tutorial-header h3 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 600;
}

.tutorial-close {
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-md);
    transition: background-color var(--transition-fast);
}

.tutorial-close:hover {
    background: rgba(255, 255, 255, 0.2);
}

.tutorial-body {
    padding: var(--space-6);
    max-height: 400px;
    overflow-y: auto;
}

.tutorial-step p {
    font-size: 1.1rem;
    margin-bottom: var(--space-4);
    color: var(--gray-800);
}

.tutorial-visual {
    margin-top: var(--space-4);
}

.tutorial-demo {
    text-align: center;
    padding: var(--space-4);
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    border: 2px dashed var(--gray-300);
}

.demo-icon {
    font-size: 3rem;
    margin-bottom: var(--space-4);
}

.demo-features {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3);
    background: white;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    color: var(--gray-800);
}

.feature-icon {
    font-size: 1.5rem;
    min-width: 2rem;
}

.demo-modules {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.demo-module {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-3);
    border-radius: var(--radius-md);
    border: 2px solid var(--gray-300);
}

.demo-module.unlocked {
    border-color: var(--success-color);
    background: var(--success-light);
}

.demo-module.locked {
    opacity: 0.6;
}

.demo-problem {
    text-align: center;
}

.demo-question {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--space-4);
    color: var(--gray-800);
}

.demo-buttons {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    margin-bottom: var(--space-3);
}

.demo-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-4);
    border: 2px solid var(--gray-300);
    border-radius: var(--radius-lg);
    background: white;
    color: var(--gray-800);
    cursor: pointer;
    transition: all var(--transition-fast);
    min-width: 100px;
}

.demo-btn:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.demo-btn.demo-true {
    border-color: var(--success-color);
}

.demo-btn.demo-false {
    border-color: var(--error-color);
}

.thumb-icon {
    font-size: 2rem;
}

.demo-note {
    font-size: 0.9rem;
    color: var(--gray-800);
    font-style: italic;
}

.demo-progress {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.progress-item {
    display: flex;
    justify-content: space-between;
    padding: var(--space-2);
    background: white;
    border-radius: var(--radius-md);
}

.progress-value {
    font-weight: 600;
    color: var(--primary-color);
}

.progress-bar-demo {
    height: 8px;
    background: var(--gray-200);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.demo-start {
    text-align: center;
}

.start-icon {
    font-size: 4rem;
    margin-bottom: var(--space-4);
}

.start-message {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: var(--space-4);
}

.start-tip {
    padding: var(--space-3);
    background: var(--warning-light);
    border-radius: var(--radius-md);
    color: var(--gray-700);
    font-size: 0.95rem;
}

.tutorial-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-6);
    border-top: 1px solid var(--gray-200);
    background: var(--gray-50);
}

.tutorial-navigation {
    display: flex;
    align-items: center;
    gap: var(--space-4);
}

.tutorial-progress {
    font-size: 0.9rem;
    color: var(--gray-800);
    min-width: 60px;
    text-align: center;
}

/* Continue Learning Section */
.module-header {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    margin-bottom: var(--space-6);
}

.continue-learning {
    text-align: center;
}

.btn-large {
    padding: var(--space-5) var(--space-8);
    font-size: 1.2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-2);
    min-width: 250px;
    margin: 0 auto;
}

.btn-icon {
    font-size: 1.5rem;
}

.btn-large small {
    font-size: 0.85rem;
    opacity: 0.8;
    font-weight: normal;
}

/* Tutorial Highlight Effect */
.tutorial-highlight {
    position: relative;
    z-index: var(--z-popover);
}

.tutorial-highlight::before {
    content: '';
    position: absolute;
    top: -4px;
    left: -4px;
    right: -4px;
    bottom: -4px;
    border: 3px solid var(--primary-color);
    border-radius: var(--radius-lg);
    animation: pulse 2s infinite;
    pointer-events: none;
}

/* Preferences Modal */
.preferences-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    -webkit-backdrop-filter: blur; backdrop-filter: blur(2px);
}

.modal-content {
    position: relative;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    max-width: 500px;
    width: 90%;
    max-height: 80vh;
    overflow: hidden;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-6);
    border-bottom: 1px solid var(--gray-200);
}

.modal-header h3 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 600;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-md);
    color: var(--gray-700);
    transition: color var(--transition-fast);
}

.modal-close:hover {
    color: var(--gray-800);
}

.modal-body {
    padding: var(--space-6);
}

.preference-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    margin-bottom: var(--space-6);
}

.preference-item {
    display: flex;
    align-items: flex-start;
    gap: var(--space-3);
    cursor: pointer;
    padding: var(--space-3);
    border-radius: var(--radius-md);
    transition: background-color var(--transition-fast);
}

.preference-item:hover {
    background: var(--gray-50);
}

.preference-item input[type="checkbox"] {
    margin-top: 2px;
}

.preference-label {
    font-weight: 500;
    color: var(--gray-800);
}

.preference-item small {
    display: block;
    color: var(--gray-700);
    font-size: 0.85rem;
    margin-top: var(--space-1);
}

.preference-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--space-3);
}

/* Tooltips */
.has-tooltip {
    position: relative;
}

.has-tooltip::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--gray-900);
    color: white;
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    font-size: 0.8rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-fast);
    z-index: var(--z-tooltip);
    margin-bottom: var(--space-2);
}

.has-tooltip::before {
    content: '';
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 5px solid transparent;
    border-top-color: var(--gray-900);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-fast);
    z-index: var(--z-tooltip);
}

.has-tooltip:hover::after,
.has-tooltip:hover::before {
    opacity: 1;
}

/* Toast Notifications */
.toast {
    animation: slideInRight 0.3s ease;
}

@keyframes slideInRight {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Preferences Button */
.preferences-btn {
    background: none !important;
    border: none !important;
    font-size: 1.2rem !important;
    padding: var(--space-2) var(--space-4) !important;
    border-radius: var(--radius-lg) !important;
    transition: var(--transition-base) !important;
    color: white !important;
    cursor: pointer !important;
}

.preferences-btn:hover {
    background-color: rgba(255, 255, 255, 0.15) !important;
    transform: translateY(-1px) !important;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15) !important;
}

/* Enhanced Module Cards */
.module-status-indicator {
    position: absolute;
    top: var(--space-4);
    right: var(--space-4);
    z-index: 1;
}

.status-badge {
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-full);
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    box-shadow: var(--shadow-sm);
}

.status-badge.completed {
    background: var(--success-light);
    color: var(--success-color);
    border: 1px solid var(--success-color);
}

.status-badge.active {
    background: var(--primary-color);
    color: white;
    animation: pulse-glow 2s infinite;
}

.status-badge.start {
    background: var(--warning-light);
    color: var(--warning-color);
    border: 1px solid var(--warning-color);
    animation: bounce 2s infinite;
}

.status-badge.locked {
    background: var(--gray-100);
    color: var(--gray-700);
    border: 1px solid var(--gray-300);
}

@keyframes pulse-glow {
    0%, 100% {
        box-shadow: var(--shadow-sm);
    }
    50% {
        box-shadow: 0 0 20px rgba(102, 126, 234, 0.4);
    }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(-3px);
    }
    60% {
        transform: translateY(-2px);
    }
}

.module-card.first-module {
    border-color: var(--warning-color);
    background: linear-gradient(135deg, white 0%, rgba(245, 158, 11, 0.05) 100%);
    position: relative;
}

.module-card.first-module::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(45deg, var(--warning-color), var(--primary-color));
    border-radius: var(--radius-2xl);
    z-index: -1;
    animation: rotate-border 3s linear infinite;
}

@keyframes rotate-border {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.module-card.locked {
    opacity: 0.7;
    cursor: not-allowed;
    background: var(--gray-50);
    border-color: var(--gray-200);
}

.module-card.locked:hover {
    transform: none;
    box-shadow: var(--shadow-lg);
}

.progress-section {
    margin-top: var(--space-4);
}

.progress-text {
    font-size: 0.9rem;
    color: var(--gray-800);
    font-weight: 500;
}

.next-action {
    font-size: 0.85rem;
    color: var(--primary-color);
    font-weight: 600;
    font-style: italic;
}

.unlock-requirement {
    font-size: 0.85rem;
    color: var(--gray-700);
    font-style: italic;
}

.module-action {
    margin-top: var(--space-5);
    text-align: center;
}

.btn-module {
    width: 100%;
    font-size: 0.95rem;
    padding: var(--space-3) var(--space-4);
}

/* Responsive improvements */
@media (max-width: 768px) {
    .module-grid {
        grid-template-columns: 1fr;
    }
    
    .btn-large {
        min-width: 200px;
        font-size: 1.1rem;
    }
    
    .button-group {
        flex-direction: column;
        gap: var(--space-3);
    }
    
    .btn-true, .btn-false, .btn-comparison {
        min-width: 120px;
        padding: var(--space-6) var(--space-8);
    }
}

/* Enhanced Tooltips */
.dynamic-tooltip {
    position: fixed;
    background: var(--gray-900);
    color: white;
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    max-width: 250px;
    z-index: var(--z-tooltip);
    opacity: 0;
    transition: opacity var(--transition-fast);
    pointer-events: none;
    box-shadow: var(--shadow-xl);
    line-height: 1.4;
}

.dynamic-tooltip::before {
    content: '';
    position: absolute;
    top: -5px;
    left: 50%;
    transform: translateX(-50%);
    border: 5px solid transparent;
    border-bottom-color: var(--gray-900);
}

.dynamic-tooltip.tooltip-below::before {
    top: auto;
    bottom: -5px;
    border-bottom-color: transparent;
    border-top-color: var(--gray-900);
}

/* Help Modal */
.help-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn var(--transition-base);
}

.help-content {
    max-width: 700px;
    max-height: 85vh;
    overflow-y: auto;
}

.help-section {
    margin-bottom: var(--space-6);
}

.help-section h4 {
    color: var(--primary-color);
    margin-bottom: var(--space-3);
    font-size: 1.1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.help-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.help-section li {
    padding: var(--space-2) 0;
    padding-left: var(--space-6);
    position: relative;
    color: var(--gray-700);
    line-height: 1.5;
}

.help-section li::before {
    content: '•';
    position: absolute;
    left: var(--space-3);
    color: var(--primary-color);
    font-weight: bold;
}

.help-section strong {
    color: var(--gray-800);
    font-weight: 600;
}

.modal-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-6);
    border-top: 1px solid var(--gray-200);
    background: var(--gray-50);
}

/* Help Button */
.help-btn {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: 0.9rem;
}

.help-btn span {
    font-size: 1rem;
}

/* Improved module card interactions */
.module-card:not(.unlocked):hover {
    cursor: help;
}

.module-card.locked::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: repeating-linear-gradient(
        45deg,
        transparent,
        transparent 10px,
        rgba(0, 0, 0, 0.02) 10px,
        rgba(0, 0, 0, 0.02) 20px
    );
    pointer-events: none;
    border-radius: var(--radius-2xl);
}

/* Progress Page Enhancements */
.module-progress-bars {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}

.module-progress-item {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    padding: var(--space-3);
    background: white;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.module-name {
    min-width: 120px;
    font-weight: 500;
    color: var(--gray-700);
    font-size: 0.9rem;
}

.progress-bar-container {
    flex: 1;
    position: relative;
    height: 24px;
    background: var(--gray-200);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: var(--primary-gradient);
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
    border-radius: var(--radius-full);
}

.progress-text {
    position: absolute;
    top: 50%;
    right: var(--space-3);
    transform: translateY(-50%);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--gray-700);
}

/* Streak Display */
.streak-display {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    align-items: center;
    padding: var(--space-6);
    background: linear-gradient(135deg, var(--success-light) 0%, white 100%);
    border-radius: var(--radius-lg);
    border: 1px solid var(--success-color);
}

.streak-info {
    text-align: center;
}

.streak-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--success-color);
    line-height: 1;
    margin-bottom: var(--space-2);
}

.streak-label {
    font-size: 1.1rem;
    color: var(--gray-700);
    font-weight: 500;
}

.calendar-days {
    display: flex;
    gap: var(--space-2);
}

.calendar-day {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-1);
    padding: var(--space-2);
}

.day-label {
    font-size: 0.8rem;
    color: var(--gray-700);
    font-weight: 500;
}

.day-indicator {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--gray-300);
    transition: background-color var(--transition-fast);
}

.calendar-day.active .day-indicator {
    background: var(--success-color);
    box-shadow: 0 0 8px rgba(16, 185, 129, 0.4);
}

/* Quick Stats */
.quick-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--space-4);
}

.stat-item {
    text-align: center;
    padding: var(--space-5);
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--gray-200);
    transition: transform var(--transition-fast);
}

.stat-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
    margin-bottom: var(--space-2);
}

.stat-label {
    font-size: 0.9rem;
    color: var(--gray-700);
    font-weight: 500;
}

/* Mobile optimizations for practice page (480px) */
@media (max-width: 480px) {
    /* Typography - larger for young learners */
    body {
        font-size: 15px;
    }
    
    /* Module cards - better touch targets */
    .module-card {
        min-height: 52px;
        padding: var(--space-5);
    }
    
    .module-card h4 {
        font-size: 1.1rem;
    }
    
    /* Problem area - larger text and padding */
    .problem-prompt {
        font-size: 1.3rem;
        padding: var(--space-5);
    }
    
    /* Answer buttons - larger touch targets */
    .btn-true, .btn-false {
        min-height: 52px;
        font-size: 1.1rem;
        padding: var(--space-4) var(--space-6);
    }
    
    .btn-comparison {
        min-height: 52px;
        font-size: 1rem;
        padding: var(--space-4);
    }
    
    .comparison-icon {
        font-size: 2.5rem;
    }
    
    /* Stats bar - stack vertically */
    .stats-bar {
        flex-direction: column;
        gap: var(--space-3);
        padding: var(--space-4);
    }
    
    .stat {
        width: 100%;
        justify-content: center;
        padding: var(--space-3);
    }
    
    .stat-label {
        font-size: 0.8rem;
    }
    
    .stat-value {
        font-size: 1.3rem;
    }
    
    /* Answer input - larger for mobile */
    .answer-input {
        min-width: 160px;
        font-size: 1.1rem;
        padding: var(--space-3) var(--space-5);
    }
    
    /* Button groups - better spacing */
    .button-group {
        gap: var(--space-3);
    }
    
    /* Feedback area - more prominent */
    .feedback-area {
        padding: var(--space-4);
        margin-bottom: var(--space-4);
    }
    
    .feedback-message {
        font-size: 1rem;
    }
}

/* Responsive adjustments for progress page */
@media (max-width: 768px) {
    .module-progress-item {
        flex-direction: column;
        align-items: stretch;
        gap: var(--space-2);
    }
    
    .module-name {
        min-width: auto;
        text-align: center;
    }
    
    .streak-display {
        padding: var(--space-4);
    }
    
    .streak-number {
        font-size: 2.5rem;
    }
    
    .calendar-days {
        justify-content: center;
    }
    
    .quick-stats {
        grid-template-columns: 1fr;
    }
}

/* Large screens (desktops, 1200px and up) */
@media (min-width: 1200px) {
    .container {
        max-width: 1200px;
    }
    
    .module-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }
    
    .features-grid, .trust-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 3rem;
    }
    
    .section-title {
        font-size: 3rem;
    }
    
    .problem-prompt {
        font-size: 2.25rem;
        max-width: 800px;
        margin: 0 auto;
    }
}

/* Ultra-wide screens (1400px and up) */
@media (min-width: 1400px) {
    .container {
        max-width: 1400px;
    }
    
    .module-grid {
        grid-template-columns: repeat(4, 1fr);
    }
    
    .hero-content {
        max-width: 900px;
    }
}