/* UE5 Optimization Deep Dive - Common Styles */
/* Version: 1.0.0 */

:root {
    /* Dark Theme (Default) - Performance/Optimization inspired */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a25;
    --bg-card-hover: #222230;
    --text-primary: #f0f0f5;
    --text-secondary: #8888a0;
    --text-muted: #555566;
    --accent-cyan: #00d4ff;
    --accent-magenta: #ff006e;
    --accent-gold: #ffd700;
    --accent-green: #00ff88;
    --accent-purple: #8b5cf6;
    --accent-orange: #ff9500;
    --accent-red: #ff4757;
    --accent-blue: #4d7cff;
    --gradient-primary: linear-gradient(135deg, #00d4ff 0%, #00ff88 50%, #ffd700 100%);
    --gradient-subtle: linear-gradient(135deg, rgba(0,212,255,0.1) 0%, rgba(0,255,136,0.1) 100%);
    --gradient-ue: linear-gradient(135deg, #2a5298 0%, #1e3c72 100%);
    --border-subtle: rgba(255,255,255,0.06);
    --shadow-glow: 0 0 60px rgba(0,212,255,0.15);
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --radius-xl: 32px;
}

[data-theme="light"] {
    --bg-primary: #f8f9fc;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #f0f2f8;
    --text-primary: #0a0a0f;
    --text-secondary: #555566;
    --text-muted: #999999;
    --border-subtle: rgba(0,0,0,0.08);
    --shadow-glow: 0 4px 40px rgba(0,0,0,0.08);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
}

/* Background Effects */
.bg-grid {
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
    background-size: 60px 60px;
    pointer-events: none;
    z-index: 0;
}

.bg-glow {
    position: fixed;
    width: 600px;
    height: 600px;
    border-radius: 50%;
    filter: blur(120px);
    opacity: 0.3;
    pointer-events: none;
    z-index: 0;
}

.bg-glow-1 {
    top: -200px;
    right: -100px;
    background: var(--accent-cyan);
}

.bg-glow-2 {
    bottom: -200px;
    left: -100px;
    background: var(--accent-green);
}

/* Header */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    padding: 20px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: linear-gradient(to bottom, var(--bg-primary), transparent);
    backdrop-filter: blur(20px);
}

.logo {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    font-weight: 900;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 16px;
}

.nav-btn {
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-subtle);
    background: var(--bg-card);
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-btn:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
    border-color: var(--accent-cyan);
}

.theme-toggle {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: 1px solid var(--border-subtle);
    background: var(--bg-card);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    transform: rotate(180deg);
    border-color: var(--accent-cyan);
}

/* Main Content */
main {
    position: relative;
    z-index: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 120px 40px 80px;
}

/* Hero Section */
.hero {
    text-align: center;
    margin-bottom: 80px;
    animation: fadeInUp 0.8s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-badge {
    display: inline-block;
    padding: 8px 20px;
    border-radius: 100px;
    background: var(--gradient-subtle);
    border: 1px solid var(--border-subtle);
    font-size: 0.85rem;
    color: var(--accent-cyan);
    font-weight: 500;
    margin-bottom: 24px;
    letter-spacing: 0.5px;
}

.hero h1 {
    font-family: 'Playfair Display', serif;
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 900;
    line-height: 1.2;
    margin-bottom: 24px;
}

.hero h1 span {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Section Styles */
.section {
    margin-bottom: 80px;
    animation: fadeInUp 0.8s ease-out;
}

.section-header {
    margin-bottom: 40px;
}

.section-number {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--accent-cyan);
    margin-bottom: 8px;
    letter-spacing: 2px;
}

.section-title {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.section-desc {
    color: var(--text-secondary);
    font-size: 1.05rem;
}

/* Content Box */
.content-box {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    padding: 48px;
    position: relative;
    overflow: hidden;
}

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

/* Cards */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-subtle);
    padding: 32px;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* Info Box */
.info-box {
    padding: 24px;
    border-radius: var(--radius-md);
    margin: 24px 0;
}

.info-box.tip {
    background: rgba(0, 255, 136, 0.1);
    border: 1px solid rgba(0, 255, 136, 0.3);
}

.info-box.warning {
    background: rgba(255, 149, 0, 0.1);
    border: 1px solid rgba(255, 149, 0, 0.3);
}

.info-box.important {
    background: rgba(255, 0, 110, 0.1);
    border: 1px solid rgba(255, 0, 110, 0.3);
}

.info-box.note {
    background: rgba(0, 212, 255, 0.1);
    border: 1px solid rgba(0, 212, 255, 0.3);
}

.info-box-title {
    font-weight: 600;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Code Block */
.code-block {
    background: #1e1e2e;
    border-radius: var(--radius-md);
    padding: 24px;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    margin: 24px 0;
    position: relative;
}

.code-block code {
    color: #cdd6f4;
    white-space: pre-wrap;
    word-wrap: break-word;
    display: block;
}

.code-block .comment { color: #6c7086; }
.code-block .keyword { color: #cba6f7; }
.code-block .string { color: #a6e3a1; }
.code-block .function { color: #89b4fa; }
.code-block .class { color: #f9e2af; }
.code-block .macro { color: #fab387; }
.code-block .number { color: #fab387; }

.code-label {
    position: absolute;
    top: 8px;
    right: 12px;
    font-size: 0.75rem;
    color: var(--text-muted);
    background: rgba(0,0,0,0.3);
    padding: 2px 8px;
    border-radius: 4px;
}

/* Tables */
.table-container {
    overflow-x: auto;
    margin: 24px 0;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-subtle);
}

th {
    background: var(--bg-card);
    font-weight: 600;
    color: var(--text-primary);
}

td {
    color: var(--text-secondary);
}

tr:hover td {
    background: var(--bg-card);
}

/* Key Points */
.key-points {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 32px;
    margin: 32px 0;
}

.key-points-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.key-points ul {
    list-style: none;
}

.key-points li {
    padding: 12px 0;
    padding-left: 28px;
    position: relative;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-subtle);
}

.key-points li:last-child {
    border-bottom: none;
}

.key-points li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent-cyan);
}

/* Navigation Footer */
.lecture-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 80px;
    padding-top: 40px;
    border-top: 1px solid var(--border-subtle);
}

.lecture-nav-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 24px;
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.3s ease;
}

.lecture-nav-btn:hover {
    background: var(--bg-card-hover);
    border-color: var(--accent-cyan);
    color: var(--text-primary);
}

.lecture-nav-btn.next {
    margin-left: auto;
}

/* Difficulty Badge */
.difficulty {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 600;
}

.difficulty.beginner {
    background: rgba(0, 255, 136, 0.2);
    color: var(--accent-green);
}

.difficulty.intermediate {
    background: rgba(255, 149, 0, 0.2);
    color: var(--accent-orange);
}

.difficulty.advanced {
    background: rgba(255, 0, 110, 0.2);
    color: var(--accent-magenta);
}

/* Footer */
footer {
    text-align: center;
    padding: 60px 40px;
    color: var(--text-muted);
    font-size: 0.9rem;
}

footer a {
    color: var(--accent-cyan);
    text-decoration: none;
}

/* Responsive */
@media (max-width: 768px) {
    header {
        padding: 16px 20px;
    }

    main {
        padding: 100px 20px 60px;
    }

    .content-box {
        padding: 24px;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .lecture-nav {
        flex-direction: column;
        gap: 16px;
    }

    .lecture-nav-btn {
        width: 100%;
        justify-content: center;
    }

    .code-block {
        padding: 16px;
        font-size: 0.8rem;
    }
}

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

.text-cyan { color: var(--accent-cyan); }
.text-magenta { color: var(--accent-magenta); }
.text-gold { color: var(--accent-gold); }
.text-green { color: var(--accent-green); }
.text-purple { color: var(--accent-purple); }
.text-orange { color: var(--accent-orange); }
.text-red { color: var(--accent-red); }
.text-blue { color: var(--accent-blue); }

.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }

/* Optimization Specific Styles */
.perf-metric {
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-green);
    font-weight: 600;
}

.perf-warning {
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-orange);
    font-weight: 600;
}

.perf-critical {
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-red);
    font-weight: 600;
}

.stat-command {
    color: var(--accent-cyan);
    font-family: 'JetBrains Mono', monospace;
    background: rgba(0, 212, 255, 0.1);
    padding: 2px 8px;
    border-radius: 4px;
}

.api-reference {
    background: var(--bg-card);
    border-left: 4px solid var(--accent-cyan);
    padding: 16px 20px;
    margin: 16px 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.api-reference-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    color: var(--accent-cyan);
    margin-bottom: 8px;
}

/* Performance Charts */
.perf-bar {
    height: 24px;
    border-radius: 4px;
    background: var(--bg-card);
    overflow: hidden;
    margin: 8px 0;
}

.perf-bar-fill {
    height: 100%;
    border-radius: 4px;
    transition: width 0.5s ease;
}

.perf-bar-fill.good {
    background: linear-gradient(90deg, var(--accent-green), var(--accent-cyan));
}

.perf-bar-fill.warning {
    background: linear-gradient(90deg, var(--accent-gold), var(--accent-orange));
}

.perf-bar-fill.critical {
    background: linear-gradient(90deg, var(--accent-orange), var(--accent-red));
}

/* =============================================
   Collapsible Code Block - 접이식 코드 블록
   ============================================= */
.code-collapsible {
    margin: 24px 0;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: #1e1e2e;
    border: 1px solid var(--border-subtle);
}

.code-collapsible-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 24px;
    background: rgba(0, 212, 255, 0.08);
    cursor: pointer;
    transition: all 0.3s ease;
    user-select: none;
}

.code-collapsible-header:hover {
    background: rgba(0, 212, 255, 0.15);
}

.code-collapsible-title {
    display: flex;
    align-items: center;
    gap: 12px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    color: var(--accent-cyan);
    font-weight: 500;
}

.code-collapsible-title::before {
    content: '</>';
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background: rgba(0, 212, 255, 0.2);
    border-radius: 8px;
    font-size: 0.75rem;
    color: var(--accent-cyan);
}

.code-collapsible-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.code-collapsible-toggle::after {
    content: '▼';
    font-size: 0.7rem;
    transition: transform 0.3s ease;
}

.code-collapsible.open .code-collapsible-toggle::after {
    transform: rotate(180deg);
}

.code-collapsible-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
}

.code-collapsible.open .code-collapsible-content {
    max-height: 2000px;
}

.code-collapsible .code-block {
    margin: 0;
    border-radius: 0;
    border-top: 1px solid var(--border-subtle);
}

/* 시각화 블록 - Visual Content First */
.visual-block {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 32px;
    margin: 24px 0;
    border: 1px solid var(--border-subtle);
    position: relative;
    overflow: hidden;
}

.visual-block::before {
    content: '📊';
    position: absolute;
    top: 16px;
    right: 16px;
    font-size: 1.5rem;
    opacity: 0.3;
}

.visual-block-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent-cyan);
    margin-bottom: 24px;
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Flow Chart Styles */
.flow-chart {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 24px;
}

.flow-chart.horizontal {
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
}

.flow-item {
    background: var(--bg-secondary);
    border: 2px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 16px 24px;
    text-align: center;
    min-width: 140px;
    transition: all 0.3s ease;
}

.flow-item:hover {
    border-color: var(--accent-cyan);
    transform: scale(1.02);
}

.flow-item.highlight {
    border-color: var(--accent-cyan);
    background: rgba(0, 212, 255, 0.1);
}

.flow-item.success {
    border-color: var(--accent-green);
    background: rgba(0, 255, 136, 0.1);
}

.flow-item.warning {
    border-color: var(--accent-orange);
    background: rgba(255, 149, 0, 0.1);
}

.flow-item.critical {
    border-color: var(--accent-red);
    background: rgba(255, 71, 87, 0.1);
}

.flow-item-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.flow-item-desc {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.flow-arrow {
    color: var(--accent-cyan);
    font-size: 1.5rem;
    animation: pulse 2s infinite;
}

.flow-chart.horizontal .flow-arrow {
    transform: rotate(-90deg);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* Diagram Container */
.diagram-container {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 32px;
    margin: 24px 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 200px;
    border: 1px dashed var(--border-subtle);
}

/* Comparison Visual */
.comparison-visual {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin: 24px 0;
}

.comparison-item {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 24px;
    border: 2px solid var(--border-subtle);
    text-align: center;
}

.comparison-item.before {
    border-color: var(--accent-red);
}

.comparison-item.after {
    border-color: var(--accent-green);
}

.comparison-label {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 12px;
}

.comparison-item.before .comparison-label {
    color: var(--accent-red);
}

.comparison-item.after .comparison-label {
    color: var(--accent-green);
}

.comparison-value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 2rem;
    font-weight: 700;
}

.comparison-item.before .comparison-value {
    color: var(--accent-red);
}

.comparison-item.after .comparison-value {
    color: var(--accent-green);
}

/* Process Steps Visual */
.process-steps {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 16px;
    margin: 24px 0;
    flex-wrap: wrap;
}

.process-step {
    flex: 1;
    min-width: 120px;
    text-align: center;
    position: relative;
}

.process-step::after {
    content: '→';
    position: absolute;
    right: -20px;
    top: 24px;
    color: var(--accent-cyan);
    font-size: 1.2rem;
}

.process-step:last-child::after {
    display: none;
}

.process-step-number {
    width: 48px;
    height: 48px;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--bg-primary);
    margin: 0 auto 12px;
    font-size: 1.1rem;
}

.process-step-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.process-step-desc {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Timeline Visual */
.timeline {
    position: relative;
    padding-left: 32px;
    margin: 24px 0;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--gradient-primary);
}

.timeline-item {
    position: relative;
    margin-bottom: 24px;
    padding-left: 24px;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -28px;
    top: 4px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--accent-cyan);
    border: 3px solid var(--bg-primary);
}

.timeline-item-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.timeline-item-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* Responsive for visual elements */
@media (max-width: 768px) {
    .comparison-visual {
        grid-template-columns: 1fr;
    }

    .process-steps {
        flex-direction: column;
        align-items: center;
    }

    .process-step::after {
        display: none;
    }

    .flow-chart.horizontal {
        flex-direction: column;
    }

    .flow-chart.horizontal .flow-arrow {
        transform: rotate(0deg);
    }
}