:root {
  --bg: #fbfaf7;
  --surface: #ffffff;
  --text: #1f2328;
  --muted: #5f6670;
  --line: #e6e2da;
  --accent: #2f6f8f;
  --radius: 14px;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #15171a;
    --surface: #1d2024;
    --text: #e8e6e3;
    --muted: #a3a9b1;
    --line: #2e3238;
    --accent: #7cc0e0;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.7 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "PingFang SC",
    "Noto Sans TC", "Noto Sans SC", "Microsoft JhengHei", sans-serif;
  -webkit-text-size-adjust: 100%;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 16px 64px;
}

header.site {
  max-width: 760px;
  margin: 0 auto;
  padding: 20px 16px 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

header.site a.home { color: var(--text); font-weight: 600; text-decoration: none; }

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

nav.lang a {
  font-size: 14px;
  padding: 4px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  text-decoration: none;
}

nav.lang a:hover { color: var(--text); border-color: var(--muted); }

h1 { font-size: 30px; line-height: 1.3; margin: 0 0 8px; }
h2 { font-size: 21px; margin: 40px 0 8px; }
h3 { font-size: 17px; margin: 24px 0 4px; }

p, li { overflow-wrap: anywhere; }

a { color: var(--accent); }

.muted { color: var(--muted); }

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

.card h3 { margin-top: 0; }

section.lang-block {
  border-top: 1px solid var(--line);
  margin-top: 48px;
  padding-top: 8px;
}

section.lang-block:first-of-type { border-top: 0; margin-top: 0; padding-top: 0; }

footer {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px 40px;
  font-size: 14px;
  color: var(--muted);
}