:root {
  --bg: #0b0d17;
  --bg-alt: #11142a;
  --surface: rgba(255,255,255,0.04);
  --border: rgba(255,255,255,0.10);
  --text: #e8eaf6;
  --muted: #9aa0c3;
  --primary: #6366f1;
  --accent: #06b6d4;
  --radius: 16px;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  color-scheme: dark;
}
:root[data-theme="light"] {
  --bg: #f7f8fc;
  --bg-alt: #eef0f8;
  --surface: #ffffff;
  --border: rgba(20,24,60,0.10);
  --text: #161a33;
  --muted: #5a6085;
  --shadow: 0 10px 30px rgba(30,40,90,.08);
  color-scheme: light;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg); color: var(--text); line-height: 1.7;
  transition: background .3s, color .3s;
}
a { color: inherit; text-decoration: none; }
.container { width: min(1120px, 100% - 32px); margin-inline: auto; }
.narrow { width: min(640px, 100% - 32px); }

/* Nav */
.nav { position: sticky; top: 0; z-index: 50; backdrop-filter: blur(12px);
  background: color-mix(in srgb, var(--bg) 75%, transparent); border-bottom: 1px solid var(--border); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 1.15rem; }
.logo-mark { width: 26px; height: 26px; border-radius: 8px; background: linear-gradient(135deg, var(--primary), var(--accent)); box-shadow: 0 0 16px var(--primary); }
.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a { color: var(--muted); font-size: .95rem; transition: color .2s; }
.nav-links a:hover { color: var(--text); }
.theme-toggle, .nav-toggle { background: none; border: 1px solid var(--border); color: var(--text);
  border-radius: 10px; width: 36px; height: 36px; cursor: pointer; font-size: 1rem; }
.nav-toggle { display: none; }

/* Hero */
.hero { position: relative; min-height: calc(100vh - 64px); display: flex; align-items: center; overflow: hidden; }
#network { position: absolute; inset: 0; width: 100%; height: 100%; opacity: .7; }
.hero::after { content: ""; position: absolute; inset: 0; pointer-events: none;
  background: radial-gradient(ellipse at 30% 40%, transparent 0%, var(--bg) 75%); }
.hero-content { position: relative; z-index: 1; padding: 80px 0; }
.eyebrow { text-transform: uppercase; letter-spacing: .2em; font-size: .8rem; color: var(--accent); margin-bottom: 16px; }
h1 { font-size: clamp(2.4rem, 6vw, 4.5rem); line-height: 1.15; font-weight: 800; }
.gradient { background: linear-gradient(90deg, var(--primary), var(--accent)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lead { max-width: 560px; margin: 24px 0 36px; color: var(--muted); font-size: 1.1rem; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }
.btn { display: inline-block; padding: 12px 26px; border-radius: 999px; font-weight: 600; cursor: pointer; border: 1px solid transparent; font-size: 1rem; transition: transform .2s, box-shadow .2s; }
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: linear-gradient(90deg, var(--primary), var(--accent)); color: #fff; box-shadow: 0 8px 24px color-mix(in srgb, var(--primary) 40%, transparent); }
.btn-ghost { border-color: var(--border); background: var(--surface); }
.stats { display: flex; gap: 48px; margin-top: 56px; flex-wrap: wrap; }
.stats dt { font-size: 2rem; font-weight: 800; }
.stats dd { color: var(--muted); font-size: .9rem; }

/* Sections */
.section { padding: 96px 0; }
.section-alt { background: var(--bg-alt); }
.section-title { font-size: clamp(1.8rem, 4vw, 2.5rem); text-align: center; }
.section-sub { text-align: center; color: var(--muted); margin: 8px 0 48px; }
.grid { display: grid; gap: 20px; }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow); transition: transform .25s, border-color .25s; }
.card:hover { transform: translateY(-4px); border-color: color-mix(in srgb, var(--primary) 60%, transparent); }
.card .icon { font-size: 2rem; margin-bottom: 12px; }
.card h3 { margin-bottom: 8px; }
.card p { color: var(--muted); }

/* Tabs */
.tabs { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; margin-bottom: 28px; }
.tab { padding: 8px 20px; border-radius: 999px; border: 1px solid var(--border); background: var(--surface); color: var(--text); cursor: pointer; font-size: .95rem; transition: all .2s; }
.tab.active { background: linear-gradient(90deg, var(--primary), var(--accent)); color: #fff; border-color: transparent; }
.tab-panels { max-width: 720px; margin: 0 auto; }
.tab-panel { display: none; text-align: center; padding: 40px 28px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); }
.tab-panel.active { display: block; animation: fade .4s ease; }
.tab-panel h3 { font-size: 1.5rem; margin-bottom: 12px; }
.tab-panel p { color: var(--muted); }
@keyframes fade { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

/* Timeline */
.timeline { list-style: none; max-width: 720px; margin: 0 auto; position: relative; }
.timeline::before { content: ""; position: absolute; left: 44px; top: 0; bottom: 0; width: 2px; background: linear-gradient(var(--primary), var(--accent)); }
.timeline li { display: flex; gap: 32px; align-items: flex-start; padding-bottom: 40px; position: relative; }
.timeline .year { flex: 0 0 90px; text-align: center; font-weight: 800; background: var(--bg); border: 2px solid var(--primary); border-radius: 999px; padding: 4px 0; position: relative; z-index: 1; }
.timeline p { color: var(--muted); }

/* Accordion */
.accordion { max-width: 720px; margin: 0 auto; display: grid; gap: 12px; }
details { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 18px 22px; }
summary { cursor: pointer; font-weight: 600; list-style: none; display: flex; justify-content: space-between; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; color: var(--accent); font-size: 1.3rem; line-height: 1; transition: transform .2s; }
details[open] summary::after { transform: rotate(45deg); }
details p { color: var(--muted); margin-top: 12px; }

/* Form */
.form { display: grid; gap: 18px; }
.form label { display: grid; gap: 6px; font-weight: 600; font-size: .95rem; }
.form input, .form textarea { font: inherit; padding: 12px 14px; border-radius: 10px; border: 1px solid var(--border); background: var(--surface); color: var(--text); }
.form input:focus, .form textarea:focus { outline: 2px solid var(--primary); outline-offset: 1px; }
.form-status { color: var(--accent); min-height: 1.5em; }

/* Footer */
.footer { border-top: 1px solid var(--border); padding: 28px 0; color: var(--muted); font-size: .9rem; }
.footer .container { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; }

/* Reveal */
.reveal { opacity: 0; transform: translateY(20px); transition: opacity .6s ease, transform .6s ease; }
.reveal.visible { opacity: 1; transform: none; }

@media (max-width: 760px) {
  .nav-toggle { display: block; }
  .nav-links { position: absolute; top: 64px; left: 0; right: 0; flex-direction: column; gap: 16px; padding: 20px; background: var(--bg); border-bottom: 1px solid var(--border); display: none; }
  .nav-links.open { display: flex; }
  .stats { gap: 28px; }
  .timeline::before { left: 34px; }
  .timeline li { gap: 18px; }
  .timeline .year { flex-basis: 70px; }
  .section { padding: 72px 0; }
}
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}
.nav-links a[aria-current="page"] { color: var(--text); font-weight: 600; }