:root {
  color-scheme: light dark;
  --bg: #f6f7fb;
  --bg-soft: #ffffff;
  --fg: #161b2c;
  --muted: #5b6478;
  --line: #e6e9f2;
  --accent: #4f46e5;
  --accent-2: #0ea5e9;
  --card-shadow: 0 1px 2px rgba(16,24,40,.05), 0 10px 28px -14px rgba(16,24,40,.22);
  --radius: 16px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f1a;
    --bg-soft: #111726;
    --fg: #e8ecf6;
    --muted: #94a0b8;
    --line: #1d2536;
    --accent: #8b8ff9;
    --accent-2: #38bdf8;
    --card-shadow: 0 1px 2px rgba(0,0,0,.35), 0 14px 36px -18px rgba(0,0,0,.65);
  }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "Source Han Sans SC", sans-serif;
  font-size: 16px;
  line-height: 1.8;
  color: var(--fg);
  background:
    radial-gradient(1100px 480px at 78% -12%, rgba(79,70,229,.10), transparent 62%),
    radial-gradient(900px 420px at 8% -6%, rgba(14,165,233,.09), transparent 58%),
    var(--bg);
  background-attachment: fixed;
}
@media (prefers-color-scheme: dark) {
  body {
    background:
      radial-gradient(1100px 480px at 78% -12%, rgba(99,102,241,.16), transparent 62%),
      radial-gradient(900px 420px at 8% -6%, rgba(56,189,248,.12), transparent 58%),
      var(--bg);
    background-attachment: fixed;
  }
}
a { color: var(--accent); }
main, header.site, footer.site { max-width: 60rem; margin: 0 auto; padding-inline: 1.25rem; }

header.site {
  display: flex; align-items: center; justify-content: space-between;
  padding-top: 1.4rem; padding-bottom: 1.4rem;
}
.brand { display: flex; align-items: center; gap: .6rem; text-decoration: none; color: var(--fg); font-weight: 800; letter-spacing: .01em; }
.logo {
  width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff; font-size: .85rem; font-weight: 800;
  box-shadow: 0 6px 16px -6px rgba(79,70,229,.6);
}
.brand .dim { color: var(--muted); font-weight: 600; }
nav a {
  margin-left: .35rem; padding: .35rem .8rem; border-radius: 999px;
  text-decoration: none; color: var(--muted); font-size: .95rem;
}
nav a:hover { color: var(--fg); background: rgba(127,127,127,.08); }
nav a.active { color: var(--fg); background: rgba(127,127,127,.10); }

.hero { padding: 3.5rem 0 2.5rem; }
.badge {
  display: inline-block; font-size: .8rem; font-weight: 600; letter-spacing: .02em;
  color: var(--accent); background: rgba(79,70,229,.10);
  border: 1px solid rgba(79,70,229,.18);
  padding: .3rem .75rem; border-radius: 999px; margin-bottom: 1.1rem;
}
.hero h1 { font-size: clamp(1.9rem, 4.5vw, 2.8rem); line-height: 1.3; margin: 0 0 .9rem; letter-spacing: 0; }
.grad {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lede { font-size: 1.08rem; color: var(--muted); max-width: 42rem; margin: 0 0 1.6rem; }
.cta { display: flex; gap: .75rem; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: .65rem 1.25rem; border-radius: 999px;
  text-decoration: none; font-weight: 600; font-size: .95rem;
  transition: transform .15s ease, box-shadow .15s ease;
}
.btn.primary {
  color: #fff; background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 10px 24px -10px rgba(79,70,229,.65);
}
.btn.ghost { color: var(--fg); border: 1px solid var(--line); background: var(--bg-soft); }
.btn:hover { transform: translateY(-2px); }

.section-title { font-size: 1rem; letter-spacing: .18em; color: var(--muted); margin: 2.2rem 0 1rem; }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 1rem; }
.card {
  background: var(--bg-soft); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.3rem 1.25rem; box-shadow: var(--card-shadow);
  transition: transform .18s ease, box-shadow .18s ease;
}
.card:hover { transform: translateY(-4px); }
.card h3 { margin: .6rem 0 .45rem; font-size: 1.08rem; line-height: 1.5; }
.card h3 a { text-decoration: none; color: var(--fg); }
.card h3 a:hover { color: var(--accent); }
.card p { margin: 0 0 .9rem; color: var(--muted); font-size: .95rem; }
.meta { font-size: .82rem; color: var(--muted); }
.tags { display: flex; gap: .4rem; flex-wrap: wrap; }
.tag {
  font-size: .72rem; font-weight: 700; letter-spacing: .03em;
  padding: .18rem .6rem; border-radius: 999px;
  color: var(--accent); background: rgba(79,70,229,.10);
}
.tag.alt { color: var(--accent-2); background: rgba(14,165,233,.12); }

article.post { max-width: 44rem; }
.post .kicker { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; margin: 2.2rem 0 1rem; }
.post h1 { font-size: clamp(1.6rem, 3.5vw, 2.1rem); line-height: 1.4; margin: 0 0 .4rem; letter-spacing: 0; }
.post .date { color: var(--muted); font-size: .9rem; }
.prose p { margin: 1.1rem 0; }
.prose h2 { margin: 2rem 0 .6rem; font-size: 1.25rem; }
.prose ul { padding-left: 1.4rem; }
.prose li { margin: .35rem 0; }
hr.sep { border: 0; border-top: 1px solid var(--line); margin: 2.2rem 0; }
.backlink { display: inline-flex; align-items: center; gap: .4rem; font-size: .95rem; text-decoration: none; color: var(--muted); }
.backlink:hover { color: var(--accent); }

.center { text-align: center; padding: 4rem 1rem; }
.big404 { font-size: clamp(4rem, 12vw, 7rem); font-weight: 900; letter-spacing: -.04em; margin: 0; line-height: 1; }
.center p { color: var(--muted); margin: 1rem auto 1.8rem; max-width: 26rem; }

footer.site {
  display: flex; justify-content: space-between; align-items: center; gap: 1rem; flex-wrap: wrap;
  margin-top: 4rem; padding-top: 1.4rem; padding-bottom: 2.4rem;
  border-top: 1px solid var(--line);
  color: var(--muted); font-size: .9rem;
}
footer.site a { color: var(--muted); text-decoration: none; }
footer.site a:hover { color: var(--accent); }

@media (max-width: 560px) {
  .hero { padding-top: 2.4rem; }
  header.site { padding-top: 1rem; padding-bottom: 1rem; }
}

@keyframes rise { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }
.hero, .card { animation: rise .5s ease both; }
.card:nth-child(2) { animation-delay: .07s; }
.card:nth-child(3) { animation-delay: .14s; }