:root {
  color-scheme: light dark;
  --canvas: #f7f8fc;
  --surface: #ffffff;
  --ink: #152c44;
  --muted: #56647c;
  --line: #dfe4ef;
  --accent: #6752dc;
  --soft: #efecff;
  --hover: #edf2fc;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --canvas: #121622; --surface: #1c2231; --ink: #edf0fa;
    --muted: #a9b5cc; --line: #323c50; --accent: #ab97ff;
    --soft: #2d2542; --hover: #27334b;
  }
}
:root[data-theme="light"] { color-scheme: light; }
:root[data-theme="dark"] {
  color-scheme: dark;
  --canvas: #121622; --surface: #1c2231; --ink: #edf0fa;
  --muted: #a9b5cc; --line: #323c50; --accent: #ab97ff;
  --soft: #2d2542; --hover: #27334b;
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--canvas); color: var(--ink);
  font: 17px/1.8 system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
header, main, footer { max-width: 850px; margin: auto; padding: 25px 28px; }
header { display: flex; align-items: center; justify-content: space-between; gap: 18px; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; font-size: 21px; font-weight: 650; }
.brand img { width: 34px; height: 34px; flex: none; user-select: none; -webkit-user-drag: none; }
nav { display: flex; flex-wrap: wrap; align-items: center; gap: 14px; font-size: 15px; }
nav a { display: inline-flex; align-items: center; min-height: 44px; }
a { color: var(--accent); text-underline-offset: 4px; overflow-wrap: anywhere; }
a:hover { text-decoration-thickness: 2px; }
a:active { text-decoration-color: var(--ink); }
a:focus-visible, select:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; border-radius: 4px; }
select { max-width: 150px; min-height: 44px; padding: 7px; border: 1px solid var(--line); border-radius: 9px; background: var(--surface); color: var(--ink); font: inherit; }
select:hover { background: var(--hover); }
select:active { background: var(--soft); }
select:disabled { opacity: .6; cursor: not-allowed; }
main { min-height: 65vh; padding-top: 40px; padding-bottom: 50px; }
h1 { font-size: clamp(28px, 5vw, 38px); line-height: 1.3; letter-spacing: -.02em; margin: 0 0 14px; }
h2 { font-size: 22px; line-height: 1.5; margin: 32px 0 10px; }
p { margin: 12px 0; overflow-wrap: anywhere; }
p a { margin-inline: .15em; }
li { margin: 8px 0; overflow-wrap: anywhere; }
li strong { margin-inline-end: .25em; }
ul, ol { padding-left: 24px; }
.meta { color: var(--muted); font-size: 15px; }
.boundary { border: 1px solid var(--line); background: var(--surface); border-radius: 15px; padding: 18px 22px; margin: 24px 0; }
.boundary p { margin: 0; }
.skip { position: absolute; left: 20px; top: -90px; padding: 10px 16px; background: var(--surface); z-index: 1; }
.skip:focus { top: 12px; }
footer { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; border-top: 1px solid var(--line); font-size: 14px; color: var(--muted); }
footer a { display: inline-flex; align-items: center; min-height: 44px; }
@media (max-width: 580px) {
  header { align-items: flex-start; flex-direction: column; gap: 6px; }
  header, main, footer { padding-left: 20px; padding-right: 20px; }
  nav { gap: 12px; }
  main { padding-top: 30px; }
  .boundary { padding: 16px; }
}