/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2c3e50;
    --secondary-color: #e74c3c;
    --accent-color: #0066cc;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #ffffff;
    --bg-light: #f8f9fa;
    --bg-dark: #1a1a1a;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --gradient-start: #003d82;
    --gradient-end: #0066cc;
}

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

h1, h2, h3, h4, h5, h6 {
    font-family: 'Noto Sans KR', sans-serif;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background-color: var(--bg-color);
    border-bottom: 1px solid #e0e0e0;
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 0.75rem 0;
}

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

.site-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary-color);
    font-family: 'Noto Sans KR', sans-serif;
}

.nav {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    color: #666;
    text-decoration: none;
    font-weight: 400;
    font-size: 0.9rem;
    transition: color 0.2s ease;
    position: relative;
}

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

.nav-link::after {
    display: none;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #003d82 0%, #0066cc 100%);
    color: white;
    padding: 5rem 0;
    text-align: center;
}

.hero-label {
    display: inline-block;
    background-color: rgba(255, 255, 255, 0.2);
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    backdrop-filter: blur(10px);
}

.hero-label i {
    margin-right: 0.5rem;
}

.hero-title {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 1rem;
    font-family: 'Noto Sans KR', sans-serif;
    line-height: 1.4;
}

.hero-subtitle {
    font-size: 2.1rem;
    margin-bottom: 2rem;
    opacity: 0.95;
    font-weight: 400;
}

.hero-meta {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    font-size: 1.9rem;
}

.hero-meta span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.hero-meta i {
    opacity: 0.8;
}

/* Video Section */
.video-section {
    padding: 2rem 0;
    background-color: var(--bg-color);
    position: relative;
}

.video-container {
    position: relative;
}

.video-sticky-wrapper {
    position: fixed;
    top: 70px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 999;
    width: 100%;
    max-width: 1200px;
    padding: 0 20px;
    pointer-events: none;
}

.video-sticky-wrapper.hidden {
    display: none;
}

.video-wrapper {
    position: relative;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding-bottom: 33.75%; /* 16:9 ratio for 600px width */
    height: 0;
    overflow: hidden;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    background-color: #000;
    pointer-events: auto;
}

.video-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 15px;
}

#static-player,
#fixed-player {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 15px;
}

/* Section Title */
.section-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 2rem;
    font-family: 'Noto Sans KR', sans-serif;
    position: relative;
    padding-bottom: 1rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, #003d82 0%, #0066cc 100%);
    border-radius: 2px;
}

.section-title i {
    margin-right: 0.5rem;
    color: var(--accent-color);
}

/* Key Summary Section */
.key-summary {
    padding: 4rem 0;
    background-color: var(--bg-color);
}

.summary-list {
    background-color: #FFF9F5;
    border-radius: 12px;
    padding: 3rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.summary-item {
    display: flex;
    gap: 2rem;
    padding: 0;
    margin-bottom: 2rem;
    transition: none;
}

.summary-item:last-child {
    margin-bottom: 0;
}

.summary-number {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background-color: #FF6B35;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
    font-weight: 700;
    font-family: 'Noto Sans KR', sans-serif;
    margin-top: 4px;
}

.summary-text {
    flex: 1;
    font-size: 1.9rem;
    line-height: 1.65;
    color: #333;
    font-weight: 400;
    font-family: 'Noto Sans KR', sans-serif;
}

/* Lecture Overview */
.lecture-overview {
    display: none;
}

/* Timeline Section */
.timeline-section {
    padding: 4rem 0 5rem 0;
    background-color: var(--bg-color);
}

.timeline {
    position: relative;
    padding-left: 0;
}

.timeline::before {
    display: none;
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 0;
    border-left: 4px solid #4A90E2;
    padding-left: 2rem;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-marker {
    position: static;
    display: inline-block;
    margin-bottom: 1rem;
}

.timeline-time {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background-color: transparent;
    color: #0066cc;
    padding: 0;
    border-radius: 0;
    font-weight: 500;
    font-size: 1.75rem;
    box-shadow: none;
    cursor: pointer;
    transition: color 0.2s ease;
}

.timeline-time:hover {
    color: #003d82;
    text-decoration: underline;
}

.timeline-time::before {
    content: '⏱';
    font-size: 2rem;
}

.timeline-content {
    background-color: transparent;
    padding: 0;
    border-radius: 0;
    box-shadow: none;
    transition: none;
}

.timeline-content:hover {
    transform: none;
    box-shadow: none;
}

.timeline-title {
    font-size: 2.2rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-family: 'Noto Sans KR', sans-serif;
    line-height: 1.5;
}

.timeline-content p {
    font-size: 1.9rem;
    line-height: 1.75;
    color: #333;
    margin-bottom: 1.5rem;
    font-family: 'Noto Sans KR', sans-serif;
}

.timeline-content p:last-child {
    margin-bottom: 0;
}

.timeline-highlight {
    background-color: transparent;
    border-left: none;
    padding: 0;
    margin: 0.8rem 0 0 0;
    border-radius: 0;
    font-weight: 400;
    color: #333;
}

/* Info Boxes */
.info-box,
.warning-box,
.highlight-box {
    margin: 1rem 0 0 0;
    padding: 0;
    border-radius: 0;
    border-left: none;
    background-color: transparent;
}

.info-box h4,
.warning-box h4,
.highlight-box h4 {
    display: none;
}

.info-box ul,
.warning-box ul,
.highlight-box ul {
    list-style: none;
    padding-left: 0;
    margin: 0;
}

.info-box li,
.warning-box li,
.highlight-box li {
    padding: 0.3rem 0;
    padding-left: 0;
    position: relative;
    font-size: 1.9rem;
    line-height: 1.75;
    color: #333;
}

.info-box li::before,
.warning-box li::before,
.highlight-box li::before {
    display: none;
}

/* Comparison Grid */
.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 1.5rem 0 0 0;
}

.comparison-item {
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    background: white;
    border: 2px solid #e0e0e0;
    margin-bottom: 0;
}

.comparison-item:last-child {
    margin-bottom: 0;
}

.comparison-korea {
    border-color: #f093fb;
    background: linear-gradient(135deg, #fff 0%, #fff5f9 100%);
}

.comparison-japan {
    border-color: #4facfe;
    background: linear-gradient(135deg, #fff 0%, #f0f9ff 100%);
}

.comparison-item h4 {
    font-size: 2.2rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    font-family: 'Noto Sans KR', sans-serif;
    color: var(--primary-color);
    padding-bottom: 1rem;
    border-bottom: 2px solid #e0e0e0;
}

.comparison-korea h4 {
    color: #d946a6;
}

.comparison-japan h4 {
    color: #0284c7;
}

.comparison-item h4 i {
    margin-right: 0.5rem;
}

.comparison-item ul {
    list-style: none;
    padding-left: 0;
}

.comparison-item li {
    padding: 0.8rem 0;
    padding-left: 1.8rem;
    position: relative;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    font-size: 1.9rem;
    line-height: 1.75;
    color: #333;
}

.comparison-item li:last-child {
    border-bottom: none;
}

.comparison-item li::before {
    content: '•';
    position: absolute;
    left: 0;
    font-weight: bold;
    font-size: 1.5rem;
}

.comparison-korea li::before {
    color: #d946a6;
}

.comparison-japan li::before {
    color: #0284c7;
}

/* Q&A Section */
.qa-section {
    margin-top: 1rem;
}

.qa-item {
    background-color: transparent;
    padding: 0;
    border-radius: 0;
    margin-bottom: 1.5rem;
    box-shadow: none;
    border-left: none;
}

.qa-item:last-child {
    margin-bottom: 0;
}

.question {
    font-size: 2.2rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.8rem;
    font-family: 'Noto Sans KR', sans-serif;
}

.question i {
    display: none;
}

.answer {
    font-size: 1.9rem;
    line-height: 1.75;
    color: #333;
}

/* Conclusion */
.conclusion {
    padding: 5rem 0;
    background: linear-gradient(135deg, #003d82 0%, #0066cc 100%);
    color: white;
}

.conclusion-text {
    font-size: 1.9rem;
    line-height: 1.75;
    margin-bottom: 1.5rem;
    font-family: 'Noto Sans KR', sans-serif;
}

/* Footer */
.footer {
    background-color: var(--bg-dark);
    color: white;
    padding: 3rem 0;
    text-align: center;
}

.footer-text {
    font-size: 1.9rem;
    margin-bottom: 1rem;
    opacity: 0.8;
}

.footer-copyright {
    font-size: 1.75rem;
    opacity: 0.6;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.1rem;
    }

    .hero-meta {
        font-size: 1rem;
        gap: 1rem;
    }

    .video-section {
        padding: 1rem 0;
    }

    .video-sticky-wrapper {
        top: 55px;
        padding: 0 10px;
    }

    .video-wrapper {
        max-width: 100%;
        padding-bottom: 56.25%;
        border-radius: 10px;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
    }

    .video-wrapper iframe {
        border-radius: 10px;
    }

    .section-title {
        font-size: 1.8rem;
    }

    .timeline {
        padding-left: 0;
    }

    .timeline-item {
        padding-left: 1rem;
        margin-bottom: 2.5rem;
        border-left: 3px solid #4A90E2;
    }

    .timeline-marker {
        position: static;
        margin-bottom: 0.5rem;
    }

    .timeline-time {
        font-size: 0.9rem;
    }

    .timeline-time::before {
        font-size: 1rem;
    }

    .timeline-title {
        font-size: 1.2rem;
    }

    .timeline-content p {
        font-size: 1rem;
        line-height: 1.7;
        margin-bottom: 1rem;
    }

    .site-title {
        font-size: 1rem;
    }

    .nav {
        gap: 1rem;
        font-size: 0.85rem;
    }

    .nav-link {
        font-size: 0.85rem;
    }

    .summary-list {
        padding: 1.5rem;
    }

    .summary-item {
        gap: 1rem;
        margin-bottom: 1.2rem;
    }

    .summary-number {
        width: 28px;
        height: 28px;
        font-size: 1rem;
        margin-top: 2px;
    }

    .summary-text {
        font-size: 1rem;
        line-height: 1.6;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .comparison-item {
        padding: 1.5rem;
    }

    .comparison-item h4 {
        font-size: 1.2rem;
        margin-bottom: 1rem;
    }

    .comparison-item li {
        font-size: 1rem;
        padding: 0.5rem 0;
        padding-left: 1.3rem;
    }

    .comparison-item li::before {
        font-size: 1.2rem;
    }

    .question {
        font-size: 1.2rem;
        margin-bottom: 0.5rem;
    }

    .answer {
        font-size: 1rem;
    }

    .conclusion-text {
        font-size: 1rem;
    }

    .footer-text {
        font-size: 1rem;
    }

    .footer-copyright {
        font-size: 0.9rem;
    }

    .info-box li,
    .warning-box li,
    .highlight-box li {
        font-size: 1rem;
    }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Animation */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.timeline-item {
    animation: fadeInUp 0.6s ease-out;
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .nav {
        display: none;
    }

    body {
        background-color: white;
    }

    .timeline::before {
        display: none;
    }
}