/* ===== CSS RESET & BASE ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette */
    --primary-600: #4f46e5;
    --primary-700: #4338ca;
    --primary-800: #3730a3;
    --primary-900: #312e81;
    
    --secondary-500: #8b5cf6;
    --secondary-600: #7c3aed;
    
    --accent-400: #34d399;
    --accent-500: #10b981;
    --accent-600: #059669;
    
    --warning-500: #f59e0b;
    --error-500: #ef4444;
    
    /* Neutral Colors */
    --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;
    
    /* Dark Mode Colors */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: rgba(30, 41, 59, 0.6);
    
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* 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);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(79, 70, 229, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Background Animation */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 50%, rgba(79, 70, 229, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(139, 92, 246, 0.1) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

.app-container {
    position: relative;
    z-index: 1;
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-md);
}

/* ===== HEADER ===== */
.header {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-lg) var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
    box-shadow: var(--shadow-xl);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.logo-section {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.logo-icon {
    font-size: 3rem;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

.logo-text h1 {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-600), var(--secondary-500));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
}

.subtitle {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

.progress-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.progress-circle {
    position: relative;
    width: 60px;
    height: 60px;
}

.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring-circle {
    transition: stroke-dashoffset 0.5s ease;
    stroke-dasharray: 163.36;
    stroke-dashoffset: 163.36;
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--primary-600);
}

.progress-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* ===== MAIN CONTENT ===== */
.main-content {
    min-height: 60vh;
}

.home-screen {
    display: none;
}

.home-screen.active {
    display: block;
    animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== HERO SECTION ===== */
.hero-section {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.2), rgba(139, 92, 246, 0.2));
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-3xl) var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.2) 0%, transparent 70%);
    animation: pulse 4s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.5; }
    50% { transform: scale(1.1); opacity: 0.8; }
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, #fff, var(--text-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto var(--spacing-2xl);
    line-height: 1.8;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xl);
    flex-wrap: wrap;
}

.stat-card {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: transform var(--transition-base);
}

.stat-card:hover {
    transform: translateY(-5px);
}

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

.stat-info {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.stat-number {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* ===== MODULE CARDS ===== */
.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.module-card {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-600), var(--secondary-500));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-base);
}

.module-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-glow);
    border-color: rgba(79, 70, 229, 0.3);
}

.module-card:hover::before {
    transform: scaleX(1);
}

.module-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.module-icon {
    font-size: 3rem;
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-5px); }
}

.module-badge {
    background: linear-gradient(135deg, var(--primary-600), var(--secondary-600));
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.module-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.module-description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.7;
}

.module-topics {
    list-style: none;
    margin-bottom: var(--spacing-xl);
}

.module-topics li {
    padding: var(--spacing-sm) 0;
    padding-left: var(--spacing-lg);
    position: relative;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.module-topics li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--accent-500);
    font-weight: 700;
}

/* ===== BUTTONS ===== */
.btn-primary {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    width: 100%;
    padding: var(--spacing-md) var(--spacing-xl);
    background: linear-gradient(135deg, var(--primary-600), var(--secondary-600));
    color: white;
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.btn-primary::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: left 0.5s;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(79, 70, 229, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-secondary:hover {
    background: var(--bg-secondary);
    border-color: var(--primary-600);
}

.btn-back {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    margin-bottom: var(--spacing-xl);
}

.btn-back:hover {
    background: var(--bg-secondary);
    transform: translateX(-5px);
}

/* ===== MODULE PROGRESS ===== */
.module-progress {
    margin-top: var(--spacing-lg);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-500), var(--accent-400));
    border-radius: var(--radius-md);
    transition: width 0.5s ease;
}

/* ===== MODULE CONTENT ===== */
.module-content {
    display: none;
}

.module-content.active {
    display: block;
    animation: fadeIn 0.5s ease-in-out;
}

.content-section {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-2xl);
    margin-bottom: var(--spacing-xl);
}

.content-section h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.content-section h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.content-section p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

.content-section ul, .content-section ol {
    margin-left: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.content-section li {
    margin-bottom: var(--spacing-sm);
    line-height: 1.7;
}

.highlight-box {
    background: linear-gradient(135deg, rgba(79, 70, 229, 0.1), rgba(139, 92, 246, 0.1));
    border-left: 4px solid var(--primary-600);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    margin: var(--spacing-lg) 0;
}

.example-box {
    background: var(--bg-tertiary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
}

.example-box pre {
    overflow-x: auto;
    color: var(--text-secondary);
}

/* ===== QUIZ STYLES ===== */
.quiz-container {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-2xl);
    margin-top: var(--spacing-xl);
}

.quiz-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.quiz-header h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

.quiz-question {
    margin-bottom: var(--spacing-2xl);
}

.question-number {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-600), var(--secondary-600));
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.question-text {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.quiz-option {
    background: var(--bg-tertiary);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.quiz-option:hover {
    border-color: var(--primary-600);
    background: var(--bg-secondary);
    transform: translateX(5px);
}

.quiz-option.selected {
    border-color: var(--primary-600);
    background: rgba(79, 70, 229, 0.2);
}

.quiz-option.correct {
    border-color: var(--accent-500);
    background: rgba(16, 185, 129, 0.2);
}

.quiz-option.incorrect {
    border-color: var(--error-500);
    background: rgba(239, 68, 68, 0.2);
}

.option-letter {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--primary-600);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.option-text {
    flex: 1;
    color: var(--text-primary);
}

.quiz-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

.quiz-result {
    text-align: center;
    padding: var(--spacing-2xl);
}

.result-score {
    font-size: 4rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--accent-500), var(--accent-400));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-md);
}

.result-message {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

.result-details {
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

/* ===== FOOTER ===== */
.footer {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: var(--spacing-3xl);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .modules-grid {
        grid-template-columns: 1fr;
    }
    
    .header-content {
        flex-direction: column;
        text-align: center;
    }
    
    .logo-text h1 {
        font-size: 1.5rem;
    }
    
    .stat-card {
        flex-direction: column;
        text-align: center;
    }
}

/* ===== UTILITY CLASSES ===== */
.hidden {
    display: none !important;
}

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

.mt-lg {
    margin-top: var(--spacing-lg);
}

.mb-lg {
    margin-bottom: var(--spacing-lg);
}