:root {
  color-scheme: light;
  --fg: #1a1a1a;
  --muted: #5c5c5c;
  --rule: #e6e6e6;
  --bg: #fcfcfb;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
}

body {
  font: 18px/1.55 "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", sans-serif;
}

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

.skip {
  position: absolute;
  left: -999px;
  top: 0;
}
.skip:focus {
  left: 1rem;
  top: 1rem;
  background: var(--bg);
}

.wrap {
  width: min(40rem, calc(100% - 2.5rem));
  margin-inline: auto;
}

header {
  padding: 4.5rem 0 2.5rem;
}

h1 {
  font-size: clamp(2.4rem, 6vw, 3.4rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin: 0 0 0.75rem;
}

h2 {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 2.5rem 0 1rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--rule);
}

h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin: 0 0 0.25rem;
}

.lede {
  font-size: 1.05rem;
  margin: 0;
}

.meta {
  color: var(--muted);
  font-size: 0.95rem;
  margin: 0.35rem 0 0;
}

.block { margin-bottom: 2rem; }

.block p { margin: 0.6rem 0 0; }

.links {
  display: flex;
  gap: 1.25rem;
}

a {
  color: inherit;
  text-underline-offset: 0.18em;
}

a:hover { text-decoration-thickness: 2px; }

.lang {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  margin-bottom: 2.5rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.lang button {
  appearance: none;
  background: none;
  border: 0;
  padding: 0;
  font: inherit;
  color: inherit;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 0.18em;
}

.lang button[aria-pressed="true"] {
  color: var(--fg);
  text-decoration: none;
  font-weight: 600;
  cursor: default;
}

footer {
  padding: 3rem 0 4rem;
  color: var(--muted);
  font-size: 0.95rem;
}