/* ============================================
   DARTLY - Complete Dart Course Stylesheet
   ============================================ */

/* CSS Variables */
:root {
    /* Colors */
    --bg-primary: #0a0e14;
    --bg-secondary: #12171f;
    --bg-card: #161c26;
    --bg-hover: #1c2431;
    --bg-code: #0d1117;
    --border: #232d3a;
    --border-light: #30363d;
    
    /* Text */
    --text-primary: #e6edf3;
    --text-secondary: #8b9bb5;
    --text-muted: #5c6e85;
    
    /* Accent */
    --accent-blue: #58a6ff;
    --accent-blue-hover: #79b8ff;
    --accent-purple: #b388ff;
    --accent-green: #3fb950;
    --accent-yellow: #d2991d;
    --accent-red: #f85149;
    --accent-orange: #ff8c00;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #58a6ff, #b388ff);
    --gradient-hero: linear-gradient(135deg, #1a1a2e, #16213e);
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(88, 166, 255, 0.2);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 50%;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
    --transition-slow: 0.35s ease;
}

/* Reset & Base */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #3a4a60;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--accent-blue);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--accent-blue-hover);
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Navigation */
.navbar {
    background: rgba(18, 23, 31, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
    cursor: pointer;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--gradient-primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color var(--transition-fast);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-primary);
}

.nav-link.active {
    background: rgba(88, 166, 255, 0.1);
}

.nav-btn {
    background: var(--gradient-primary);
    color: white;
    border: none;
    padding: 0.5rem 1.2rem;
    border-radius: 20px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.nav-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
}

.mobile-menu {
    display: none;
    flex-direction: column;
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
}

.mobile-menu a {
    padding: var(--spacing-sm) 0;
    color: var(--text-secondary);
    text-decoration: none;
}

/* Buttons */
.btn-primary, .btn-secondary {
    display: inline-block;
    padding: 0.8rem 2rem;
    border-radius: 25px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    text-decoration: none;
    border: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.btn-secondary {
    background: var(--bg-card);
    border: 1px solid var(--border);
    color: var(--text-primary);
}

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

.btn-lg {
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
}

/* Hero Section */
.hero {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-xl);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
    min-height: calc(100vh - 64px);
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-lg);
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 500px;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
}

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

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    min-width: 100px;
}

.stat-number {
    font-size: 1.8rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.hero-visual {
    display: flex;
    justify-content: center;
}

.code-preview {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    width: 100%;
    max-width: 450px;
    box-shadow: var(--shadow-lg);
}

.code-dots {
    display: flex;
    gap: 8px;
    padding: 12px 16px;
    background: #161b22;
    border-bottom: 1px solid var(--border);
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: var(--radius-full);
}

.dot.red { background: #ff5f56; }
.dot.yellow { background: #ffbd2e; }
.dot.green { background: #27c93f; }

.code-preview pre {
    padding: var(--spacing-lg);
    margin: 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.8;
    color: #c9d1d9;
}

.code-preview .keyword { color: #ff7b72; }
.code-preview .function { color: #d2a8ff; }
.code-preview .string { color: #a5d6ff; }
.code-preview .variable { color: #ffa657; }

/* Features Section */
.features {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-xl);
}

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

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: all var(--transition-normal);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-blue);
}

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.feature-card h3 {
    margin-bottom: var(--spacing-sm);
}

.feature-card p {
    font-size: 0.9rem;
}

/* Lessons Grid */
.lessons-overview {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-xl);
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.lesson-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: all var(--transition-normal);
    cursor: pointer;
}

.lesson-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-blue);
}

.lesson-number {
    display: inline-block;
    background: var(--gradient-primary);
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.lesson-card h3 {
    margin-bottom: var(--spacing-sm);
    font-size: 1.2rem;
}

.lesson-card p {
    font-size: 0.9rem;
    margin-bottom: var(--spacing-lg);
}

.lesson-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* CTA Section */
.cta {
    text-align: center;
    padding: var(--spacing-2xl);
    background: var(--gradient-hero);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
}

.cta h2 {
    margin-bottom: var(--spacing-md);
}

.cta p {
    margin-bottom: var(--spacing-xl);
    font-size: 1.1rem;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: var(--spacing-2xl) var(--spacing-xl);
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: var(--spacing-xl);
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: var(--spacing-md);
}

.footer-section a {
    display: block;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    font-size: 0.9rem;
}

.footer-section a:hover {
    color: var(--accent-blue);
}

.footer-bottom {
    max-width: 1400px;
    margin: var(--spacing-xl) auto 0;
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ============================================
   LESSON PAGE STYLES
   ============================================ */

.lesson-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--spacing-xl);
    min-height: calc(100vh - 64px);
}

/* Sidebar */
.lesson-sidebar {
    position: sticky;
    top: 84px;
    height: fit-content;
    max-height: calc(100vh - 100px);
    overflow-y: auto;
}

.sidebar-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.sidebar-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--border);
}

.lesson-nav-list {
    list-style: none;
}

.lesson-nav-item {
    padding: 0.6rem var(--spacing-md);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 2px;
    border: 1px solid transparent;
}

.lesson-nav-item:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.lesson-nav-item.active {
    background: var(--bg-hover);
    color: var(--accent-blue);
    border-color: var(--accent-blue);
    font-weight: 500;
}

.lesson-nav-item.completed {
    color: var(--accent-green);
}

/* Progress */
.progress-section {
    margin-top: var(--spacing-lg);
}

.progress-bar {
    background: var(--bg-card);
    border-radius: 10px;
    height: 8px;
    margin: var(--spacing-sm) 0;
    overflow: hidden;
}

.progress-fill {
    background: var(--gradient-primary);
    height: 100%;
    border-radius: 10px;
    transition: width 0.5s ease;
}

.progress-text {
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* Content Area */
.lesson-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.lesson-header {
    padding: var(--spacing-xl) var(--spacing-2xl);
    border-bottom: 1px solid var(--border);
    background: linear-gradient(to bottom, var(--bg-card), var(--bg-secondary));
}

.lesson-header h1 {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
}

.lesson-meta-info {
    display: flex;
    gap: var(--spacing-lg);
    color: var(--text-secondary);
    font-size: 0.9rem;
    flex-wrap: wrap;
}

.lesson-body {
    padding: var(--spacing-2xl);
}

.lesson-body h2 {
    font-size: 1.5rem;
    margin: var(--spacing-xl) 0 var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border);
}

.lesson-body h3 {
    font-size: 1.2rem;
    margin: var(--spacing-lg) 0 var(--spacing-sm);
    color: var(--accent-blue);
}

.lesson-body p {
    margin-bottom: var(--spacing-md);
}

.lesson-body ul,
.lesson-body ol {
    margin: var(--spacing-md) 0;
    padding-left: 1.5rem;
    color: var(--text-secondary);
}

.lesson-body li {
    margin-bottom: var(--spacing-sm);
}

/* Code Blocks */
.code-block {
    background: var(--bg-code);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-md);
    margin: var(--spacing-lg) 0;
    overflow: hidden;
}

.code-header {
    background: #161b22;
    padding: 0.75rem var(--spacing-md);
    border-bottom: 1px solid var(--border-light);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.code-lang {
    font-size: 0.8rem;
    color: #8b949e;
    text-transform: uppercase;
    font-weight: 500;
}

.copy-btn {
    background: #21262d;
    border: 1px solid #30363d;
    color: #c9d1d9;
    padding: 0.3rem 0.8rem;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.copy-btn:hover {
    background: #30363d;
}

.code-block pre {
    padding: var(--spacing-lg);
    overflow-x: auto;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 0.85rem;
    line-height: 1.6;
    color: #c9d1d9;
    margin: 0;
}

code {
    background: #1c2431;
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    color: #e6edf3;
}

/* Info Cards */
.info-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    border-left: 4px solid var(--accent-blue);
}

.info-card.tip {
    border-left-color: var(--accent-green);
}

.info-card.warning {
    border-left-color: var(--accent-yellow);
}

.info-card.error {
    border-left-color: var(--accent-red);
}

.info-card-title {
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

/* Quiz */
.quiz-section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
}

.quiz-question {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

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

.quiz-option {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 1rem 1.2rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    color: var(--text-secondary);
}

.quiz-option:hover {
    background: var(--bg-hover);
    border-color: var(--accent-blue);
    color: var(--text-primary);
}

.quiz-option.correct {
    background: rgba(63, 185, 80, 0.15);
    border-color: var(--accent-green);
    color: var(--accent-green);
}

.quiz-option.wrong {
    background: rgba(248, 81, 73, 0.15);
    border-color: var(--accent-red);
    color: var(--accent-red);
}

.quiz-feedback {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
    font-weight: 500;
}

/* Video Container */
.video-container {
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    max-width: 100%;
    margin: var(--spacing-lg) 0;
    border-radius: var(--radius-md);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: var(--radius-md);
}

/* Navigation Buttons */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border);
    gap: var(--spacing-md);
}

/* Hidden Answer */
.hidden-answer {
    background: var(--bg-card);
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.hidden-answer summary {
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    color: var(--accent-blue);
    padding: var(--spacing-sm) 0;
    user-select: none;
}

.hidden-answer summary:hover {
    color: var(--accent-blue-hover);
}

.answer-content {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-lg);
    background: var(--bg-code);
    border-radius: var(--radius-md);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    line-height: 1.6;
    color: #c9d1d9;
    white-space: pre-wrap;
    overflow-x: auto;
}

/* Project Section */
.project-section {
    background: var(--gradient-hero);
    border: 2px solid var(--accent-blue);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    margin: var(--spacing-xl) 0;
}

.project-title {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, #ffd700, #ff8c00);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-subtitle {
        max-width: 100%;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-visual {
        order: -1;
    }
    
    .lesson-container {
        grid-template-columns: 1fr;
    }
    
    .lesson-sidebar {
        position: static;
        max-height: none;
    }
    
    .lesson-nav-list {
        display: flex;
        flex-wrap: wrap;
        gap: var(--spacing-xs);
    }
    
    .lesson-nav-item {
        flex: 1 1 auto;
        text-align: center;
        min-width: 120px;
    }
}

/* --- Interactive Section Wrapper --- */
.interactive-section {
  margin: 2.5rem 0;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  transition: border-color 0.2s ease;
}
.interactive-section:hover {
  border-color: var(--accent-blue);
}

/* --- Step Header --- */
.step-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--border);
}
.step-number {
  background: var(--accent-blue);
  color: #fff;
  font-weight: 700;
  padding: 0.3rem 0.8rem;
  border-radius: 20px;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* --- Onboarding Wizard --- */
.onboarding-wizard {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-card));
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  margin: 2rem 0;
  text-align: center;
}
.wizard-step {
  display: none;
}
.wizard-step.active {
  display: block;
}
.wizard-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}
.wizard-actions {
  margin-top: 2rem;
  display: flex;
  justify-content: center;
  gap: 1rem;
}

/* --- Terminal Simulator --- */
.terminal-simulator {
  background: #1e1e1e;
  border-radius: 10px;
  overflow: hidden;
  font-family: 'JetBrains Mono', monospace;
  margin: 1.5rem 0;
  border: 1px solid var(--border);
}
.terminal-header {
  background: #2d2d2d;
  padding: 0.5rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.terminal-dots span {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  margin-right: 5px;
}
.terminal-dots span:nth-child(1) { background: #ff5f56; }
.terminal-dots span:nth-child(2) { background: #ffbd2e; }
.terminal-dots span:nth-child(3) { background: #27c93f; }
.terminal-body {
  padding: 1rem;
  color: #d4d4d4;
  font-size: 0.9rem;
  line-height: 1.6;
}
.terminal-line {
  margin-bottom: 0.25rem;
}
.terminal-run-btn {
  background: var(--accent-blue);
  border: none;
  color: white;
  padding: 0.5rem 1rem;
  margin: 0.5rem 1rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
}

/* --- Code Playground / Editors --- */
.code-playground,
.live-code-editor,
.code-block.interactive {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
}
.playground-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 1rem;
  background: rgba(255,255,255,0.05);
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
}
.code-editor textarea,
textarea[id] {
  width: 100%;
  min-height: 180px;
  background: transparent;
  border: none;
  padding: 1rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-color);
  resize: vertical;
  outline: none;
}
.live-output {
  padding: 1rem;
  background: rgba(0,0,0,0.2);
  border-top: 1px solid var(--border);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.9rem;
}
.playground-actions {
  display: flex;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background: rgba(0,0,0,0.1);
}

/* --- Variable Visualizer / Cards --- */
.var-type-cards {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin: 1rem 0;
}
.var-card {
  flex: 1 1 120px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  transition: transform 0.2s, border-color 0.2s;
}
.var-card:hover {
  transform: translateY(-3px);
  border-color: var(--accent-blue);
}

/* --- Quiz Sections --- */
.quiz-section,
.quiz-game-advanced {
  margin: 2rem 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
}
.quiz-options {
  display: grid;
  gap: 0.75rem;
  margin: 1rem 0;
}
.quiz-option {
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  padding: 0.75rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
}
.quiz-option:hover {
  background: rgba(0,120,200,0.1);
  border-color: var(--accent-blue);
}
.quiz-option.correct {
  background: rgba(76,175,80,0.15);
  border-color: #4CAF50;
}
.quiz-option.incorrect {
  background: rgba(244,67,54,0.15);
  border-color: #f44336;
}
.quiz-feedback {
  margin-top: 0.75rem;
  font-weight: 500;
}
.quiz-stats {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 1rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* --- Progress Bars --- */
.progress-bar-visual {
  font-family: 'JetBrains Mono', monospace;
  background: rgba(0,0,0,0.2);
  padding: 0.5rem;
  border-radius: 4px;
}

/* --- Sliders & Inputs --- */
input[type="range"] {
  width: 100%;
  margin: 0.5rem 0;
  appearance: none;
  -webkit-appearance: none;
  background: transparent;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 6px;
  background: var(--border);
  border-radius: 3px;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  background: var(--accent-blue);
  border-radius: 50%;
  margin-top: -6px;
  cursor: pointer;
}
input[type="text"],
input[type="number"],
input[type="date"],
select {
  background: rgba(0,0,0,0.2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  color: var(--text-color);
  font-family: inherit;
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.2s;
}
input:focus,
select:focus {
  border-color: var(--accent-blue);
}

/* --- Buttons (Interactive) --- */
.interactive-mode-btn {
  background: var(--accent-blue);
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  width: 100%;
  text-align: center;
  font-size: 0.9rem;
}
.interactive-mode-btn:hover {
  opacity: 0.9;
}

/* --- Status Code Grid --- */
.status-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
}
.status-btn {
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  cursor: pointer;
  transition: background 0.2s;
}
.status-btn.success { border-color: #4CAF50; color: #4CAF50; }
.status-btn.redirect { border-color: #FF9800; color: #FF9800; }
.status-btn.client-error { border-color: #f44336; color: #f44336; }
.status-btn.server-error { border-color: #9C27B0; color: #9C27B0; }

/* --- File Tree Explorer --- */
.file-tree-interactive {
  background: rgba(0,0,0,0.1);
  border-radius: 8px;
  padding: 0.75rem;
  font-family: 'JetBrains Mono', monospace;
}
.folder,
.file {
  padding: 0.2rem 0;
  cursor: pointer;
}

/* --- Dependency Graph Visualizer --- */
.graph-node {
  display: inline-block;
  padding: 0.5rem 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 20px;
  font-weight: 500;
}
.graph-edge {
  display: flex;
  align-items: center;
  margin: 0.5rem 0;
}

/* --- Mixin/Composer blocks --- */
.mixin-block {
  padding: 0.5rem 1rem;
  background: rgba(0,120,200,0.1);
  border: 1px solid var(--accent-blue);
  border-radius: 8px;
  cursor: pointer;
  margin: 0.25rem;
  text-align: center;
  transition: background 0.2s;
}
.mixin-block.selected {
  background: var(--accent-blue);
  color: white;
}

/* --- Log Console --- */
.log-console {
  background: #1a1a1a;
  border-radius: 10px;
  padding: 1rem;
  height: 200px;
  overflow-y: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85rem;
  color: #b0b0b0;
  border: 1px solid var(--border);
  margin: 1rem 0;
}
.log-entry {
  margin-bottom: 0.25rem;
}

/* --- Certificate Preview --- */
.certificate {
  background: linear-gradient(135deg, #f9f9f9, #ffffff);
  border: 2px solid gold;
  padding: 2rem;
  border-radius: 12px;
  text-align: center;
  max-width: 600px;
  margin: 2rem auto;
  color: #333;
  box-shadow: 0 8px 32px rgba(0,0,0,0.1);
}
.cert-seal {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent-blue);
}

/* --- Celebration Confetti --- */
.confetti-piece {
  position: fixed;
  z-index: 9999;
  pointer-events: none;
}

/* --- Toast Notification --- */
.toast-notification {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--accent-blue);
  color: white;
  padding: 1rem 1.5rem;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  z-index: 9999;
  animation: slideInRight 0.3s ease, fadeOut 0.3s 2.7s forwards;
}

.top-progress {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(255,255,255,0.05);
    padding: 0 1rem;
    border-radius: 20px;
    height: 30px;
    min-width: 200px;
}
.top-progress-fill {
    height: 6px;
    background: var(--accent-blue);
    border-radius: 3px;
    transition: width 0.3s ease;
}
.top-progress-text {
    font-size: 0.8rem;
    color: var(--text-muted);
    white-space: nowrap;
}
.reset-progress-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
    border-radius: 50%;
    width: 24px;
    height: 24px;
    font-size: 1rem;
    cursor: pointer;
    line-height: 1;
}
.reset-progress-btn:hover {
    background: rgba(244,67,54,0.1);
    border-color: #f44336;
}

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


@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .mobile-menu.active {
        display: flex;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-stats {
        gap: var(--spacing-md);
    }
    
    .stat {
        min-width: 80px;
        padding: var(--spacing-sm);
    }
    
    .stat-number {
        font-size: 1.4rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .lesson-body {
        padding: var(--spacing-lg);
    }
    
    .lesson-header {
        padding: var(--spacing-lg);
    }
    .interactive-section {
    padding: 1rem;
  }
  .var-type-cards {
    flex-direction: column;
  }
  .quiz-stats {
    flex-wrap: wrap;
    gap: 0.5rem;
  }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .btn-lg {
        padding: 0.8rem 1.5rem;
        font-size: 0.95rem;
    }
    
    .features-grid,
    .lessons-grid {
        grid-template-columns: 1fr;
    }
}

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



.fade-in {
    animation: fadeIn 0.3s ease;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateX(-20px); }
    to { opacity: 1; transform: translateX(0); }
}

.slide-in {
    animation: slideIn 0.3s ease;
}

/* Print Styles */
@media print {
    .navbar, .lesson-sidebar, .footer, .lesson-navigation {
        display: none;
    }
    
    .lesson-container {
        grid-template-columns: 1fr;
    }
    
    body {
        background: white;
        color: black;
    }
}