:root {
  --bg: #0b1020;
  --bg-dark: #070b16;
  --card: rgba(255,255,255,0.06);
  --border: rgba(255,255,255,0.12);
  --text: rgba(255,255,255,0.92);
  --muted: rgba(255,255,255,0.65);
  --accent: #5b8cff;
  --radius: 14px;
  --maxw: 1120px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial;
  background: radial-gradient(1200px 600px at 20% -10%, rgba(91,140,255,.25), transparent 60%), var(--bg);
  color: var(--text);
}

/* 通用 */
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.narrow { max-width: 820px; }
.section { padding: 80px 0; }
.section-dark { background: var(--bg-dark); }
.section-title { font-size: 32px; margin: 0 0 12px; }
.section-desc { color: var(--muted); margin-bottom: 40px; }
.paragraph { color: var(--muted); line-height: 1.8; margin-bottom: 18px; }

/* 协议/文档页 */
.doc-back { color: var(--accent); text-decoration: none; display: inline-block; margin-bottom: 24px; }
.doc-back:hover { color: var(--text); }
.doc-content h2 { color: var(--text); font-size: 20px; margin: 32px 0 12px; }
.doc-content h2:first-of-type { margin-top: 0; }
.doc-content h3 { color: var(--text); font-size: 18px; margin: 32px 0 12px; }
.doc-content h3:first-of-type { margin-top: 0; }
.doc-list { color: var(--muted); line-height: 1.8; margin: 0 0 18px; padding-left: 24px; }
.doc-list li { margin-bottom: 8px; }
.doc-content a { color: var(--accent); text-decoration: none; }
.doc-content a:hover { text-decoration: underline; }
.footer-note a { color: var(--muted); text-decoration: none; }
.footer-note a:hover { color: var(--text); }

/* Header */
.header {
  position: sticky;
  top: 0;
  background: rgba(11,16,32,.8);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 10;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
}
.logo-mark {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, #5b8cff, #7aa2ff);
  border-radius: 8px;
}
.nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 20px;
}
.nav a:hover { color: var(--text); }

/* Hero */
.hero {
  padding: 120px 0;
  text-align: center;
}
.hero h1 {
  font-size: 48px;
  margin-bottom: 16px;
}
.hero-subtitle {
  color: var(--muted);
  font-size: 18px;
  max-width: 680px;
  margin: 0 auto 32px;
}
.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
}

/* Buttons */
.btn {
  padding: 12px 22px;
  border-radius: var(--radius);
  text-decoration: none;
  font-weight: 600;
}
.btn.primary {
  background: var(--accent);
  color: #fff;
}
.btn.ghost {
  border: 1px solid var(--border);
  color: var(--text);
}

/* Cards */
.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}
.card h3 { margin-top: 0; }

/* Tech */
.tech-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.tech-item h4 { margin-bottom: 8px; }

/* Contact */
.contact-box {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  line-height: 1.8;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  color: var(--muted);
}

/* Responsive */
@media (max-width: 900px) {
  .card-grid, .tech-list { grid-template-columns: 1fr; }
  .hero h1 { font-size: 36px; }
}