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

:root {
    --bg-primary: #0f0e1a;
    --bg-secondary: #1a1a2e;
    --bg-card: rgba(26, 26, 46, 0.85);
    --gold: #c9a84c;
    --gold-muted: #d4c5a0;
    --green: #2d6a4f;
    --text-primary: #f0ece3;
    --text-secondary: #b8b0a0;
    --font-serif: 'Playfair Display', serif;
    --font-sans: 'Inter', sans-serif;
    --radius: 12px;
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.navbar {
    background: rgba(15, 14, 26, 0.9);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(201, 168, 76, 0.15);
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-serif);
    font-size: 1.3rem;
    color: var(--gold);
    text-decoration: none;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.logo:hover {
    color: var(--gold-muted);
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.3s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--gold);
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: var(--gold);
    color: var(--bg-primary);
}

.btn-primary:hover {
    background: var(--gold-muted);
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(201, 168, 76, 0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--gold);
    border: 1px solid var(--gold);
}

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

.btn-lg {
    padding: 14px 36px;
    font-size: 1.1rem;
}

.btn-sm {
    padding: 6px 16px;
    font-size: 0.85rem;
}

/* Hero */
.hero {
    padding: 80px 0 60px;
    text-align: center;
    background: radial-gradient(ellipse at center, rgba(201, 168, 76, 0.08) 0%, transparent 70%);
}

.hero h1 {
    font-family: var(--font-serif);
    font-size: 3.2rem;
    color: var(--gold);
    margin-bottom: 16px;
    font-weight: 700;
}

.hero .subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto 32px;
}

/* Papers Section */
.papers-section {
    padding: 40px 0 60px;
}

.papers-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 24px;
}

.paper-card {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    padding: 28px;
    border-radius: var(--radius);
    border: 1px solid rgba(201, 168, 76, 0.1);
    transition: transform 0.3s, border-color 0.3s;
}

.paper-card:hover {
    transform: translateY(-4px);
    border-color: rgba(201, 168, 76, 0.3);
}

.paper-card.featured {
    grid-row: span 2;
    border-color: rgba(201, 168, 76, 0.3);
}

.paper-card.external {
    opacity: 0.8;
}

.paper-card.external:hover {
    opacity: 1;
}

.badge {
    display: inline-block;
    padding: 2px 12px;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    background: var(--gold);
    color: var(--bg-primary);
    margin-bottom: 12px;
}

.badge.external {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--text-secondary);
}

.paper-card h2 {
    font-family: var(--font-serif);
    font-size: 1.6rem;
    margin-bottom: 8px;
}

.paper-card h3 {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    margin-bottom: 6px;
}

.paper-card .author {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 12px;
}

.paper-card .teaser {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 16px;
}

.card-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

/* Footer */
.footer {
    border-top: 1px solid rgba(201, 168, 76, 0.1);
    padding: 24px 0;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

/* Responsive */
@media (max-width: 900px) {
    .papers-grid {
        grid-template-columns: 1fr;
    }
    .paper-card.featured {
        grid-row: auto;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        gap: 12px;
        padding: 20px 0;
        width: 100%;
    }
    .nav-links.open {
        display: flex;
    }
    .menu-toggle {
        display: block;
    }
    .hero h1 {
        font-size: 2.2rem;
    }
    .hero .subtitle {
        font-size: 1rem;
    }
}