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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    line-height: 1.6;
    color: #333;
    background: #f5f5f5;
}

a {
    color: #1976d2;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

/* Header */
header {
    background: #1a1a2e;
    color: white;
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

header img {
    height: 50px;
}

nav {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
}

nav a {
    color: white;
    font-weight: 500;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: white;
    text-align: center;
    padding: 4rem 2rem;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero p {
    font-size: 1.25rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto 2rem;
}

.hero video {
    max-width: 100%;
    width: 600px;
    border-radius: 8px;
    margin-top: 2rem;
}

/* CTA Section */
.cta {
    background: white;
    padding: 3rem 2rem;
    text-align: center;
}

.cta h2 {
    margin-bottom: 1.5rem;
    color: #1a1a2e;
}

.btn {
    display: inline-block;
    background: #1976d2;
    color: white;
    padding: 0.75rem 2rem;
    border-radius: 4px;
    font-weight: 600;
    transition: background 0.3s;
}

.btn:hover {
    background: #1565c0;
    text-decoration: none;
}

/* Cards Section */
.cards-section {
    padding: 3rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.cards-section h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: #1a1a2e;
}

.cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}

.card img {
    width: 48px;
    height: 48px;
    margin-bottom: 1rem;
}

.card h3 {
    color: #1a1a2e;
    margin-bottom: 0.5rem;
}

.card p {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.card .btn {
    font-size: 0.85rem;
    padding: 0.5rem 1rem;
}

/* Modules Section */
.modules {
    background: white;
    padding: 3rem 2rem;
}

.modules h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: #1a1a2e;
}

.modules-list {
    max-width: 800px;
    margin: 0 auto;
    display: grid;
    gap: 1rem;
}

.module-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1rem;
    background: #f8f9fa;
    border-radius: 8px;
    border-left: 4px solid #1976d2;
}

.module-item::before {
    content: "\2713";
    color: #1976d2;
    font-weight: bold;
    font-size: 1.2rem;
}

.module-item strong {
    color: #1a1a2e;
}

.module-item span {
    color: #666;
}

/* Citations Section */
.citations {
    padding: 3rem 2rem;
    background: #f5f5f5;
}

.citations h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: #1a1a2e;
}

.bibtex-container {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.copy-btn {
    position: absolute;
    top: 12px;
    right: 12px;
    background: #44475a;
    color: #f8f8f2;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: background 0.2s, transform 0.1s;
    z-index: 10;
}

.copy-btn:hover {
    background: #6272a4;
}

.copy-btn:active {
    transform: scale(0.95);
}

.copy-btn.copied {
    background: #50fa7b;
    color: #282a36;
}

.copy-btn svg {
    width: 16px;
    height: 16px;
}

.bibtex {
    background: #282a36;
    color: #f8f8f2;
    padding: 1.5rem;
    padding-top: 3.5rem;
    border-radius: 8px;
    overflow-x: auto;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.85rem;
    line-height: 1.5;
    max-height: 400px;
    overflow-y: auto;
}

.bibtex pre {
    white-space: pre-wrap;
    word-wrap: break-word;
}

/* About Section */
.about {
    background: white;
    padding: 3rem 2rem;
}

.about h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: #1a1a2e;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
}

.about-content p {
    margin-bottom: 1rem;
    color: #444;
}

/* Footer */
footer {
    background: #1a1a2e;
    color: white;
    padding: 2rem;
    text-align: center;
}

footer .badges {
    margin-bottom: 1rem;
}

footer .badges img {
    margin: 0 0.5rem;
}

footer .links {
    margin-bottom: 1rem;
}

footer .links a {
    color: #90caf9;
    margin: 0 1rem;
}

footer .copyright {
    opacity: 0.8;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.75rem;
    }

    .hero p {
        font-size: 1rem;
    }

    header {
        justify-content: center;
        text-align: center;
    }
}