:root {
  --bg: #f6f6f8;
  --card: #ffffff;
  --text: #1c1c1e;
  --muted: #6c6c70;
  --line: #e3e3e8;
  --accent: #3a6df0;
  --accent-soft: #eaf0fe;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111113;
    --card: #1c1c1e;
    --text: #f2f2f7;
    --muted: #a1a1a8;
    --line: #2c2c30;
    --accent: #6f95ff;
    --accent-soft: #1e2a47;
  }
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.7 -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px 64px; }

header.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 20px 0;
}

.brand { display: flex; align-items: center; gap: 10px; font-weight: 600; color: var(--text); }
.brand:hover { text-decoration: none; }
.brand img { width: 32px; height: 32px; border-radius: 8px; }

.lang-switch { display: flex; gap: 4px; font-size: 14px; }
.lang-switch a {
  padding: 4px 10px;
  border-radius: 999px;
  color: var(--muted);
}
.lang-switch a:hover { text-decoration: none; color: var(--text); }
html:not([data-lang="en"]) .lang-switch a[data-set="zh"],
html[data-lang="en"] .lang-switch a[data-set="en"] {
  background: var(--accent-soft);
  color: var(--accent);
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 28px 24px;
}

h1 { font-size: 28px; line-height: 1.3; margin: 0 0 6px; }
h2 { font-size: 19px; margin: 32px 0 8px; }
h3 { font-size: 16px; margin: 22px 0 4px; }
p, ul { margin: 8px 0; }
ul { padding-left: 1.3em; }
li { margin: 4px 0; }

.meta { color: var(--muted); font-size: 14px; margin-bottom: 20px; }

.highlight {
  background: var(--accent-soft);
  border-radius: 12px;
  padding: 14px 16px;
  margin: 16px 0;
}
.highlight ul { margin: 0; }

.contact {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  background: var(--accent-soft);
  border-radius: 12px;
  padding: 16px;
  margin: 16px 0 8px;
}
.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 600;
}
.btn:hover { text-decoration: none; opacity: .9; }

details {
  border-top: 1px solid var(--line);
  padding: 12px 0;
}
details:last-of-type { border-bottom: 1px solid var(--line); }
summary { cursor: pointer; font-weight: 600; list-style: none; position: relative; padding-right: 24px; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; position: absolute; right: 0; top: 0; color: var(--muted); font-weight: 400; }
details[open] summary::after { content: "−"; }
details > div { color: var(--text); padding-top: 6px; }

.links { display: grid; gap: 12px; margin-top: 20px; }
.links a {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px 18px;
  color: var(--text);
  font-weight: 600;
}
.links a span { display: block; color: var(--muted); font-weight: 400; font-size: 14px; }
.links a:hover { text-decoration: none; border-color: var(--accent); }

footer { color: var(--muted); font-size: 13px; text-align: center; margin-top: 28px; }
footer a { color: var(--muted); }

/* 中英文切换：默认显示中文，html[data-lang="en"] 时显示英文 */
[lang="en"].l { display: none; }
html[data-lang="en"] [lang="zh-Hans"].l { display: none; }
html[data-lang="en"] [lang="en"].l { display: block; }
html[data-lang="en"] span[lang="en"].l { display: inline; }

@media (max-width: 480px) {
  .card { padding: 22px 16px; border-radius: 14px; }
  h1 { font-size: 24px; }
}