:root {
  color-scheme: light dark;
  --background: #f5f7fb;
  --surface: #ffffff;
  --text: #172033;
  --muted: #5f6b7d;
  --border: #dfe5ee;
  --accent: #2457d6;
  --accent-strong: #173f9f;
  --notice: #f1f5ff;
  --shadow: 0 18px 50px rgba(34, 52, 84, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  background: var(--background);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(36, 87, 214, 0.08), transparent 28rem),
    var(--background);
}

a {
  color: var(--accent);
  text-underline-offset: 0.18em;
}

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

a:focus-visible {
  border-radius: 0.2rem;
  outline: 3px solid rgba(36, 87, 214, 0.35);
  outline-offset: 3px;
}

.site-header,
.site-footer,
main {
  width: min(100% - 2rem, 760px);
  margin-inline: auto;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1.5rem 1rem;
}

.brand {
  color: var(--text);
  font-size: 1.15rem;
  font-weight: 750;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1rem;
  font-size: 0.92rem;
}

.site-nav a[aria-current="page"] {
  color: var(--text);
  font-weight: 650;
  text-decoration: none;
}

main {
  padding-block: 1rem 3rem;
}

.page-card {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 1.25rem;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.page-intro,
.language-section {
  padding: clamp(1.4rem, 4vw, 2.5rem);
}

.page-intro {
  border-bottom: 1px solid var(--border);
}

.language-section + .language-section {
  border-top: 1px solid var(--border);
}

h1,
h2,
h3 {
  line-height: 1.25;
  text-wrap: balance;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 8vw, 3rem);
  letter-spacing: -0.045em;
}

h2 {
  margin: 0 0 1rem;
  font-size: clamp(1.35rem, 5vw, 1.75rem);
}

h3 {
  margin: 1.8rem 0 0.45rem;
  font-size: 1rem;
  letter-spacing: 0.025em;
  text-transform: uppercase;
}

[lang="zh-Hans"] h3 {
  text-transform: none;
}

p {
  margin: 0.65rem 0 0;
}

.eyebrow,
.updated {
  color: var(--muted);
  font-size: 0.9rem;
}

.eyebrow {
  margin: 0 0 0.4rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.contact {
  margin-block: 1.35rem;
  padding: 1rem 1.1rem;
  border-left: 4px solid var(--accent);
  border-radius: 0.25rem 0.75rem 0.75rem 0.25rem;
  background: var(--notice);
  font-size: 1.05rem;
  font-weight: 650;
  overflow-wrap: anywhere;
}

.language-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  margin-top: 1rem;
  font-size: 0.92rem;
}

.site-footer {
  padding-block: 0 2rem;
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
}

@media (max-width: 520px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .page-card {
    border-radius: 1rem;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #0d1320;
    --surface: #151d2c;
    --text: #edf2fb;
    --muted: #aeb9ca;
    --border: #2b374b;
    --accent: #8db0ff;
    --accent-strong: #b8ccff;
    --notice: #1b2946;
    --shadow: none;
  }
}