:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1c1c1f;
  --muted: #66666e;
  --line: #e7e7ec;
  --card: #f6f6f8;
  --accent: #E5484D;
  --accent-strong: #C4343A;
  --link: #C4343A;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121214;
    --fg: #ececf0;
    --muted: #a1a1aa;
    --line: #2b2b30;
    --card: #1c1c20;
    --accent-strong: #E5484D;
    --link: #FF6B70;
  }
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

:lang(zh) { font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif; line-height: 1.75; }
:lang(ar) { font-family: -apple-system, BlinkMacSystemFont, "SF Arabic", "Geeza Pro", "Segoe UI", Tahoma, "Noto Sans Arabic", sans-serif; line-height: 1.8; }

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 16px;
}

.top {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--fg);
  text-decoration: none;
  font-weight: 600;
}

.mark {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.langs {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.langs button {
  font: inherit;
  font-size: 14px;
  line-height: 1;
  min-height: 32px;
  padding: 8px 11px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--fg);
  cursor: pointer;
}

.langs button:hover { border-color: var(--muted); }

.langs button[aria-pressed="true"] {
  background: var(--accent-strong);
  border-color: var(--accent-strong);
  color: #fff;
}

a:focus-visible,
.langs button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

main { padding: 32px 0 0; }

h1 {
  font-size: 2rem;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin: 0 0 0.75rem;
}

h2 {
  font-size: 1.25rem;
  line-height: 1.35;
  margin: 2.25rem 0 0.5rem;
}

h3 {
  font-size: 1.0625rem;
  line-height: 1.4;
  margin: 1.5rem 0 0.25rem;
}

p, ul { margin: 0 0 1rem; }

ul { padding-inline-start: 1.25rem; }

li { margin: 0.4rem 0; }

a {
  color: var(--link);
  text-underline-offset: 2px;
}

.lead { font-size: 1.125rem; }

.meta {
  color: var(--muted);
  font-size: 0.9375rem;
  margin-bottom: 1.5rem;
}

.card {
  background: var(--card);
  border-radius: 12px;
  padding: 16px 20px;
  margin: 0 0 1rem;
}

.card p:last-child { margin-bottom: 0; }

footer {
  margin-top: 3rem;
  padding: 20px 0 40px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9375rem;
}

footer nav { margin-bottom: 0.25rem; }

footer a { color: var(--muted); }

footer a[aria-current="page"] {
  color: var(--fg);
  font-weight: 600;
  text-decoration: none;
}

footer p { margin: 0; }

@media (min-width: 600px) {
  h1 { font-size: 2.25rem; }
  main { padding-top: 40px; }
}