:root {
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --dark: #10151c;
  --ink: #141a22;
  --body: #3d4653;
  --muted: #6b7482;
  --line: #e3e6eb;
  --brand: #2a6df4;
  --brand-dark: #1f56c4;
  --sans: -apple-system, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--body);
  font-family: var(--sans); font-size: 16px; line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--brand); text-decoration: none; }
a:hover { color: var(--brand-dark); }
h1, h2, h3 { color: var(--ink); margin: 0; line-height: 1.3; }

.container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* header */
.site-header { background: var(--dark); color: #c9d1db; border-bottom: 1px solid #222a35; }
.site-header .container { display: flex; align-items: center; height: 64px; gap: 32px; }
.logo { display: flex; align-items: center; gap: 10px; color: #fff; font-weight: 600; font-size: 17px; }
.logo:hover { color: #fff; }
.logo img { width: 24px; height: 24px; display: block; }
.nav { display: flex; align-items: center; gap: 28px; margin-left: auto; font-size: 15px; }
.nav a { color: #c9d1db; }
.nav a:hover { color: #fff; }
.nav .lang-switch { font-size: 14px; border: 1px solid #39424f; border-radius: 4px; padding: 3px 10px; }

/* hero */
.hero { background: var(--dark); color: #c9d1db; padding: 88px 0 96px; }
.hero h1 { color: #fff; font-size: 44px; font-weight: 700; letter-spacing: -.01em; max-width: 15em; }
.hero p { font-size: 18px; max-width: 40em; margin: 22px 0 0; color: #aeb7c3; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 36px; }
.btn {
  display: inline-block; padding: 11px 22px; border-radius: 4px; font-size: 15px; font-weight: 500;
  border: 1px solid transparent; transition: background .15s, border-color .15s, color .15s;
}
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); color: #fff; }
.btn-ghost { border-color: #3a4350; color: #e6ebf1; }
.btn-ghost:hover { border-color: #8a95a3; color: #fff; }

/* sections */
.section { padding: 80px 0; border-bottom: 1px solid var(--line); }
.section.alt { background: var(--bg-alt); }
.section h2 { font-size: 28px; font-weight: 700; }
.section .intro { max-width: 44em; margin: 12px 0 0; color: var(--muted); }

.grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; margin-top: 40px; background: var(--line); border: 1px solid var(--line); }
.grid > div { background: var(--bg); padding: 28px 30px; }
.grid h3 { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.grid p { margin: 0; }

/* spec table */
.spec { width: 100%; border-collapse: collapse; margin-top: 36px; background: var(--bg); border: 1px solid var(--line); font-size: 15px; }
.spec th, .spec td { text-align: left; padding: 13px 20px; border-bottom: 1px solid var(--line); vertical-align: top; }
.spec th { width: 28%; color: var(--muted); font-weight: 500; background: #fbfbfc; }
.spec td { color: var(--ink); }
.spec tr:last-child th, .spec tr:last-child td { border-bottom: 0; }
.spec code { font-family: var(--mono); font-size: 14px; }

/* roadmap */
.roadmap { display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px; margin-top: 40px; list-style: none; padding: 0; }
.roadmap li { border-top: 3px solid var(--line); padding-top: 16px; display: flex; flex-direction: column; }
.roadmap li.done { border-top-color: var(--ink); }
.roadmap li.current { border-top-color: var(--brand); }
.roadmap .phase { font-size: 13px; color: var(--muted); }
.roadmap h3 { font-size: 16px; font-weight: 600; margin: 4px 0 6px; }
.roadmap p { margin: 0; font-size: 14px; color: var(--muted); line-height: 1.6; }
.roadmap .status { display: block; margin-top: auto; padding-top: 10px; font-size: 13px; color: var(--muted); }
.roadmap li.done .status { color: var(--ink); }
.roadmap li.current .status { color: var(--brand); }

/* docs */
.docs { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 36px; }
.doc { border: 1px solid var(--line); border-radius: 6px; padding: 24px; background: var(--bg); display: flex; flex-direction: column; }
.doc h3 { font-size: 17px; font-weight: 600; }
.doc p { margin: 8px 0 18px; color: var(--muted); font-size: 15px; flex: 1; }
.doc .links { display: flex; gap: 16px; font-size: 15px; font-weight: 500; }
.doc .soon { font-size: 14px; color: var(--muted); }

.notice { margin-top: 28px; font-size: 14px; color: var(--muted); }

/* footer */
.site-footer { background: var(--dark); color: #8b95a3; font-size: 14px; padding: 36px 0; }
.site-footer .container { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; }
.site-footer a { color: #c9d1db; }

@media (max-width: 900px) {
  .roadmap { grid-template-columns: 1fr 1fr; }
  .docs { grid-template-columns: 1fr; }
}
@media (max-width: 680px) {
  .nav a:not(.lang-switch) { display: none; }
  .hero { padding: 56px 0 64px; }
  .hero h1 { font-size: 30px; }
  .hero p { font-size: 16px; }
  .section { padding: 56px 0; }
  .section h2 { font-size: 24px; }
  .grid { grid-template-columns: 1fr; }
  .grid > div { padding: 22px; }
  .roadmap { grid-template-columns: 1fr; }
  .spec th, .spec td { padding: 11px 14px; }
  .spec th { width: 36%; }
}

/* hero stats */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); margin: 64px 0 0; border-top: 1px solid #263040; }
.stats div { padding: 22px 24px 0 0; }
.stats dt { color: #fff; font-size: 26px; font-weight: 600; line-height: 1.2; }
.stats dd { margin: 4px 0 0; font-size: 14px; color: #8b95a3; }
@media (max-width: 680px) { .stats { grid-template-columns: 1fr 1fr; row-gap: 8px; margin-top: 44px; } .stats dt { font-size: 22px; } }