:root {
  --bg: #f5f5f0;
  --surface: #ffffff;
  --text: #0b0d12;
  --muted: rgba(11, 13, 18, 0.68);
  --border: rgba(11, 13, 18, 0.12);
  --brand: #0b0d12;
  --brand-2: #2844ff;
  --radius: 16px;
  --shadow: 0 18px 40px rgba(11, 13, 18, 0.08);
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    "Courier New", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial,
    "Apple Color Emoji", "Segoe UI Emoji";
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--text);
  background: radial-gradient(1200px 600px at 20% -10%, rgba(40, 68, 255, 0.08), transparent 55%),
    radial-gradient(900px 500px at 80% 0%, rgba(11, 13, 18, 0.06), transparent 55%),
    var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
  text-underline-offset: 4px;
}

.container {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--border);
  background: rgba(245, 245, 240, 0.72);
  backdrop-filter: blur(10px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.brand-mark {
  width: 28px;
  height: 28px;
  flex: 0 0 auto;
}

.brand-title {
  font-weight: 800;
  letter-spacing: -0.02em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-link {
  padding: 8px 10px;
  border-radius: 999px;
  border: 1px solid transparent;
  color: rgba(11, 13, 18, 0.72);
  font-weight: 600;
}

.nav-link:hover {
  background: rgba(11, 13, 18, 0.04);
  text-decoration: none;
}

.nav-link.is-active {
  border-color: var(--border);
  background: rgba(255, 255, 255, 0.78);
  color: var(--text);
}

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.72);
  border-radius: 999px;
  overflow: hidden;
}

.lang-btn {
  appearance: none;
  border: 0;
  padding: 8px 10px;
  background: transparent;
  color: rgba(11, 13, 18, 0.72);
  font-weight: 700;
  cursor: pointer;
}

.lang-btn[aria-pressed="true"] {
  background: rgba(11, 13, 18, 0.92);
  color: #fff;
}

main {
  padding: 26px 0 36px;
}

h1 {
  margin: 0 0 10px;
  font-size: 36px;
  letter-spacing: -0.03em;
}

.lead {
  margin: 0 0 22px;
  color: var(--muted);
  line-height: 1.7;
  font-size: 16px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 14px;
  margin: 18px 0 26px;
}

.card {
  grid-column: span 12;
  padding: 18px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.78);
  box-shadow: var(--shadow);
}

.card h2 {
  margin: 0 0 8px;
  font-size: 18px;
}

.card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.7;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 999px;
  background: rgba(40, 68, 255, 0.1);
  border: 1px solid rgba(40, 68, 255, 0.22);
  color: rgba(11, 13, 18, 0.88);
  font-weight: 700;
  margin: 10px 0 0;
}

.mono {
  font-family: var(--mono);
}

section {
  margin: 18px 0;
}

section h3 {
  margin: 0 0 10px;
  font-size: 16px;
  letter-spacing: -0.01em;
}

ul {
  margin: 8px 0 0;
  padding-left: 18px;
  line-height: 1.8;
  color: rgba(11, 13, 18, 0.88);
}

li {
  margin: 6px 0;
}

.callout {
  border: 1px solid rgba(11, 13, 18, 0.16);
  background: rgba(255, 255, 255, 0.62);
  border-radius: var(--radius);
  padding: 14px 16px;
  line-height: 1.7;
  color: rgba(11, 13, 18, 0.88);
}

.footer {
  border-top: 1px solid var(--border);
  padding: 18px 0 22px;
  color: var(--muted);
  font-size: 13px;
}

.footer a {
  color: rgba(11, 13, 18, 0.78);
}

[data-lang="zh"] .lang-en {
  display: none;
}

[data-lang="en"] .lang-zh {
  display: none;
}

@media (min-width: 720px) {
  .card.two-col {
    grid-column: span 6;
  }

  h1 {
    font-size: 44px;
  }
}