/* IStars Space — AI Infrastructure */

:root {
    --bg: #0a0a0f;
    --bg-alt: #111118;
    --surface: #1a1a24;
    --border: #2a2a38;
    --text: #e4e4ec;
    --text-muted: #8888a0;
    --accent: #6c5ce7;
    --accent-glow: #a29bfe;
    --gradient: linear-gradient(135deg, #6c5ce7 0%, #a29bfe 50%, #00cec9 100%);
    --radius: 12px;
    --radius-sm: 8px;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* Nav */
.nav {
    position: fixed; top: 0; left: 0; right: 0; z-index: 100;
    background: rgba(10,10,15,0.85);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--border);
}

.nav-inner {
    max-width: 1200px; margin: 0 auto;
    padding: 0 24px; height: 60px;
    display: flex; align-items: center; justify-content: space-between;
}

.logo {
    font-size: 1.1rem; font-weight: 700; color: var(--text); text-decoration: none;
    letter-spacing: -0.02em;
}

.nav-links { display: flex; gap: 32px; align-items: center; }
.nav-links a { color: var(--text-muted); text-decoration: none; font-size: 0.9rem; transition: color 0.2s; }
.nav-links a:hover { color: var(--text); }

.btn-nav {
    background: var(--surface); border: 1px solid var(--border);
    padding: 6px 16px; border-radius: 20px; font-size: 0.85rem !important;
}
.btn-nav:hover { background: var(--border) !important; }

/* Sections */
.section { padding: 120px 24px; max-width: 1200px; margin: 0 auto; }
.section-dark { background: var(--bg-alt); max-width: none; }
.section-dark > * { max-width: 1200px; margin-left: auto; margin-right: auto; }
.section-dark .section-header { margin-left: auto; margin-right: auto; padding: 0 24px; }
.section-dark .papers { padding: 0 24px; }
.section-dark .about-grid { padding: 0 24px; }

.section-header { text-align: center; margin-bottom: 64px; }
.section-header .tag {
    display: inline-block; font-size: 0.8rem; font-weight: 600; text-transform: uppercase;
    letter-spacing: 0.08em; color: var(--accent-glow);
    background: rgba(108,92,231,0.1); border: 1px solid rgba(108,92,231,0.2);
    padding: 4px 12px; border-radius: 20px; margin-bottom: 16px;
}
.section-header h2 { font-size: 2.5rem; font-weight: 700; letter-spacing: -0.03em; margin-bottom: 12px; }
.section-header p { font-size: 1.1rem; color: var(--text-muted); max-width: 600px; margin: 0 auto; }

/* Hero */
.hero {
    min-height: 100vh; display: flex; align-items: center;
    padding: 120px 24px 80px; max-width: 1200px; margin: 0 auto;
}
.hero-content { max-width: 800px; }
.hero h1 { font-size: 4rem; font-weight: 800; letter-spacing: -0.04em; line-height: 1.1; margin-bottom: 24px; }
.gradient { background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-sub { font-size: 1.2rem; color: var(--text-muted); margin-bottom: 40px; line-height: 1.7; max-width: 640px; }

.hero-actions { display: flex; gap: 16px; margin-bottom: 64px; }

.btn-primary {
    display: inline-block; background: var(--accent); color: #fff;
    padding: 14px 32px; border-radius: var(--radius-sm); font-weight: 600;
    text-decoration: none; font-size: 1rem; transition: background 0.2s, box-shadow 0.2s;
}
.btn-primary:hover { background: #7c6ff7; box-shadow: 0 0 30px rgba(108,92,231,0.3); }

.btn-secondary {
    display: inline-block; background: var(--surface); color: var(--text);
    padding: 14px 32px; border-radius: var(--radius-sm); font-weight: 600;
    text-decoration: none; font-size: 1rem; border: 1px solid var(--border);
    transition: background 0.2s;
}
.btn-secondary:hover { background: var(--border); }

.hero-stats { display: flex; gap: 48px; }
.stat strong { display: block; font-size: 1.8rem; font-weight: 700; letter-spacing: -0.02em; }
.stat span { display: block; font-size: 0.85rem; color: var(--text-muted); margin-top: 4px; }

/* Cards */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 24px; }
.card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 32px; transition: border-color 0.2s, transform 0.2s;
}
.card:hover { border-color: var(--accent); transform: translateY(-2px); }
.card-icon { font-size: 2rem; margin-bottom: 16px; }
.card h3 { font-size: 1.2rem; font-weight: 600; margin-bottom: 8px; letter-spacing: -0.02em; }
.card p { font-size: 0.95rem; color: var(--text-muted); line-height: 1.6; }

/* Papers */
.papers { display: flex; flex-direction: column; gap: 24px; }
.paper {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 28px 32px;
}
.paper-venue {
    display: inline-block; font-size: 0.75rem; font-weight: 600; text-transform: uppercase;
    color: var(--accent-glow); background: rgba(108,92,231,0.1); padding: 2px 10px;
    border-radius: 12px; margin-bottom: 12px;
}
.paper h4 { font-size: 1.15rem; font-weight: 600; margin-bottom: 8px; letter-spacing: -0.02em; }
.paper p { font-size: 0.95rem; color: var(--text-muted); margin-bottom: 12px; line-height: 1.6; }
.paper-link { color: var(--accent-glow); text-decoration: none; font-size: 0.9rem; font-weight: 500; }

/* Code block */
.code-block {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 32px; overflow-x: auto; max-width: 720px; margin: 0 auto;
}
.code-block pre { margin: 0; }
.code-block code {
    font-family: "SF Mono", "Fira Code", "Fira Mono", Menlo, monospace;
    font-size: 0.88rem; line-height: 1.8; color: var(--text);
}
.code-block .c { color: #666; }

.docs-cta { text-align: center; margin-top: 24px; }
.docs-cta a { color: var(--accent-glow); text-decoration: none; font-weight: 500; }

/* About */
.about-grid { display: grid; grid-template-columns: 2fr 1fr; gap: 64px; align-items: start; }
.about-text p { font-size: 1rem; color: var(--text-muted); margin-bottom: 16px; line-height: 1.7; }

.about-locations { display: flex; flex-direction: column; gap: 12px; }
.location {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm);
    padding: 16px 20px; display: flex; justify-content: space-between; align-items: center;
}
.location strong { font-weight: 600; }
.location span { font-size: 0.8rem; color: var(--text-muted); }

/* Contact */
.contact-links { display: flex; justify-content: center; gap: 32px; flex-wrap: wrap; }
.contact-item {
    color: var(--text); text-decoration: none; font-size: 1rem;
    background: var(--surface); border: 1px solid var(--border); padding: 12px 24px;
    border-radius: var(--radius-sm); transition: border-color 0.2s;
}
.contact-item:hover { border-color: var(--accent); }

/* Footer */
.footer { border-top: 1px solid var(--border); padding: 40px 24px; }
.footer-inner {
    max-width: 1200px; margin: 0 auto;
    display: flex; justify-content: space-between; align-items: center;
    flex-wrap: wrap; gap: 16px;
}
.footer-brand { font-weight: 700; font-size: 0.95rem; }
.footer-links { display: flex; gap: 24px; }
.footer-links a { color: var(--text-muted); text-decoration: none; font-size: 0.85rem; transition: color 0.2s; }
.footer-links a:hover { color: var(--text); }
.footer-copy { font-size: 0.85rem; color: var(--text-muted); }

/* Responsive */
@media (max-width: 768px) {
    .hero h1 { font-size: 2.5rem; }
    .hero-stats { flex-wrap: wrap; gap: 24px; }
    .section { padding: 80px 20px; }
    .section-header h2 { font-size: 1.8rem; }
    .about-grid { grid-template-columns: 1fr; gap: 32px; }
    .nav-links { gap: 16px; }
    .nav-links a:not(.btn-nav) { display: none; }
    .code-block { padding: 20px; }
    .code-block code { font-size: 0.78rem; }
}