:root {
  --bg: #fcfcfc;
  --bg-alt: #f4f4f5;
  --fg: #18181b;
  --fg-muted: #71717a;
  --accent: #2563eb;
  --accent-fg: #ffffff;
  --border: #e4e4e7;
  --card: #ffffff;
  --mono: "SF Mono", "JetBrains Mono", "Fira Code", ui-monospace, Menlo, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html { scroll-behavior: smooth; overflow-x: clip; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}

.mono { font-family: var(--mono); }
.small { font-size: 0.8125rem; color: var(--fg-muted); }
.dot { color: var(--fg-muted); padding: 0 0.35rem; }

a { color: inherit; text-decoration: none; }
a:hover { color: var(--accent); }

.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.875rem 1.5rem;
  background: rgba(252, 252, 252, 0.92);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: 700;
  font-size: 1.0625rem;
  letter-spacing: -0.01em;
}

.brand-mark { font-family: var(--mono); color: var(--accent); font-weight: 400; }

.nav-right { display: flex; align-items: center; gap: 0.75rem; }

.lang-toggle {
  font-family: var(--sans);
  font-size: 0.8125rem;
  padding: 0.3125rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: transparent;
  color: var(--fg-muted);
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
}
.lang-toggle:hover { border-color: var(--accent); color: var(--accent); }

.github-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4375rem;
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 0.3125rem 0.875rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  transition: border-color 0.15s, color 0.15s;
}
.github-btn:hover { border-color: var(--accent); color: var(--accent); }

main { max-width: 64rem; margin: 0 auto; padding: 0 1.5rem; }

.hero { padding: 6.5rem 0 5.5rem; text-align: center; }

.hero-kicker {
  font-size: 0.8125rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin-bottom: 1.25rem;
}

.hero-title {
  font-size: clamp(2.75rem, 7vw, 4.5rem);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.03em;
}

.hero-sub {
  max-width: 40rem;
  margin: 1.75rem auto 0;
  font-size: 1.125rem;
  color: var(--fg-muted);
}

.hero-cta {
  display: flex;
  gap: 0.875rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 2.5rem;
}

.btn {
  display: inline-block;
  padding: 0.6875rem 1.375rem;
  border-radius: 0.5rem;
  font-size: 0.9375rem;
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
}
.btn:hover { transform: translateY(-1px); color: var(--accent); }

.btn-primary { background: var(--fg); color: var(--bg); }
.btn-primary:hover { color: var(--bg); box-shadow: 0 6px 20px rgba(0,0,0,0.14); }

.btn-ghost { border-color: var(--border); color: var(--fg); }

.hero-platforms {
  margin-top: 2.75rem;
  font-size: 0.875rem;
  color: var(--fg-muted);
  letter-spacing: 0.06em;
}

.section { padding: 4.5rem 0; }
.section-alt { background: var(--bg-alt); }
main > .section-alt { margin-left: calc(50% - 50vw); margin-right: calc(50% - 50vw); padding-left: max(1.5rem, calc(50vw - 32rem)); padding-right: max(1.5rem, calc(50vw - 32rem)); }

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 2.25rem;
}

.section-note {
  margin-top: 2rem;
  color: var(--fg-muted);
  font-size: 0.9375rem;
  max-width: 44rem;
}

.grid { display: grid; gap: 1rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 1.375rem 1.5rem;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.card:hover { border-color: #c8c8cd; box-shadow: 0 2px 12px rgba(0,0,0,0.05); }
.card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 0.5rem; }
.card p { font-size: 0.9375rem; color: var(--fg-muted); }

.section-alt .card { background: var(--bg); }

.card-tag { color: var(--accent); font-size: 0.75rem; margin-bottom: 0.75rem; }
.card-accent { border-top: 2px solid var(--fg); }

.card-platform .mono { margin-bottom: 0.75rem; }
.card-platform h3 { margin-bottom: 0.25rem; }
.card-platform p:last-of-type { margin-bottom: 0.875rem; }
.card-link { font-size: 0.875rem; font-weight: 600; color: var(--accent); }

.card-link-wrapper { display: block; }
.card-link-wrapper:hover { border-color: var(--accent); }
.card-link-wrapper h3 { color: var(--fg); }
.card-link-wrapper:hover h3 { color: var(--accent); }

.arch { display: flex; flex-direction: column; gap: 0.5rem; max-width: 40rem; }

.arch-tier {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  padding: 0.875rem 1.25rem;
  background: var(--bg);
  transition: border-color 0.15s;
}
.arch-tier:hover { border-color: var(--fg); }
.arch-tier-strong { border-width: 2px; }
.arch-tier-base { border-style: dashed; }
.arch-name { font-weight: 700; font-size: 0.875rem; }
.arch-desc { font-size: 0.8125rem; color: var(--fg-muted); }

.quickstart {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.code-block {
  background: #17171b;
  color: #e4e4e7;
  border-radius: 0.75rem;
  padding: 1.375rem 1.5rem;
  font-size: 0.8125rem;
  line-height: 1.8;
  white-space: pre-wrap;
  word-break: break-all;
}

.code-comment { color: #71717a; display: block; margin-bottom: 0.5rem; word-break: keep-all; }

.footer {
  border-top: 1px solid var(--border);
  padding: 2.5rem 1.5rem;
  text-align: center;
}

@media (max-width: 56rem) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .quickstart { grid-template-columns: 1fr; }
}

@media (max-width: 40rem) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .hero { padding: 4rem 0 3.5rem; }
  .section { padding: 3.25rem 0; }
}