:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fc;
  --text: #1a2233;
  --muted: #5b6577;
  --border: #e3e8f0;
  --accent: #4338ca;
  --accent-soft: #eef0ff;
  --accent-dark: #3730a3;
  --code-bg: #0f172a;
  --radius: 12px;
  --maxw: 1120px;
  --contentw: 760px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font-family: var(--font); font-size: 17px; line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; border-radius: 8px; }

/* header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.92); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; justify-content: space-between; height: 64px;
}
.brand { font-weight: 800; font-size: 22px; color: var(--text); letter-spacing: -.5px; }
.brand span { color: var(--accent); }
.brand:hover { text-decoration: none; }
.nav a { margin-left: 24px; color: var(--muted); font-weight: 600; font-size: 15px; }
.nav a:hover { color: var(--accent); text-decoration: none; }

/* hero */
.hero {
  background: linear-gradient(135deg, #eef0ff 0%, #f6f8fc 60%, #ffffff 100%);
  border-bottom: 1px solid var(--border);
}
.hero-inner { max-width: var(--maxw); margin: 0 auto; padding: 64px 20px 56px; }
.hero h1 { font-size: 42px; line-height: 1.2; letter-spacing: -1px; margin: 0 0 16px; max-width: 720px; }
.hero p { font-size: 19px; color: var(--muted); max-width: 640px; margin: 0 0 28px; }
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  padding: 12px 26px; border-radius: 10px; font-weight: 700; font-size: 16px;
}
.btn:hover { background: var(--accent-dark); text-decoration: none; color: #fff; }
.btn-ghost {
  display: inline-block; padding: 12px 26px; border-radius: 10px; font-weight: 700;
  font-size: 16px; border: 1px solid var(--border); color: var(--text); margin-left: 12px; background: #fff;
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }

/* layout */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 40px 20px; }
.section-title { font-size: 26px; letter-spacing: -.5px; margin: 8px 0 20px; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 20px; }
.card {
  border: 1px solid var(--border); border-radius: var(--radius); padding: 22px;
  background: #fff; display: flex; flex-direction: column; transition: box-shadow .2s, transform .2s;
}
.card:hover { box-shadow: 0 8px 28px rgba(67,56,202,.10); transform: translateY(-2px); }
.card .kicker {
  font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em;
  color: var(--accent); margin-bottom: 8px;
}
.card h3 { margin: 0 0 8px; font-size: 19px; line-height: 1.4; }
.card h3 a { color: var(--text); }
.card p { color: var(--muted); font-size: 15px; margin: 0 0 12px; flex: 1; }
.card .meta { font-size: 13px; color: var(--muted); }
.cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; margin-top: 8px; }
.cat-card {
  background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px; color: var(--text);
}
.cat-card:hover { text-decoration: none; border-color: var(--accent); }
.cat-card h3 { margin: 0 0 6px; font-size: 17px; }
.cat-card p { margin: 0; font-size: 14px; color: var(--muted); }

/* article */
.article { max-width: var(--contentw); margin: 0 auto; }
.breadcrumb { font-size: 14px; color: var(--muted); margin-bottom: 12px; }
.article h1 { font-size: 36px; line-height: 1.25; letter-spacing: -.8px; margin: 0 0 14px; }
.article-meta { color: var(--muted); font-size: 14px; margin-bottom: 28px; display: flex; gap: 16px; flex-wrap: wrap; }
.article h2 { font-size: 27px; letter-spacing: -.4px; margin: 44px 0 14px; padding-top: 8px; border-top: 1px solid var(--border); }
.article h2:first-of-type { border-top: none; }
.article h3 { font-size: 21px; margin: 30px 0 10px; }
.article p, .article li { overflow-wrap: break-word; }
.article ul, .article ol { padding-left: 24px; }
.article li { margin-bottom: 6px; }
.toc {
  background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 22px; margin: 0 0 32px; font-size: 15px;
}
.toc strong { display: block; margin-bottom: 8px; font-size: 14px; text-transform: uppercase; letter-spacing: .06em; }
.toc nav ul { margin: 0; padding-left: 18px; }
.toc nav li { margin-bottom: 4px; }
pre { background: var(--code-bg); border-radius: 10px; padding: 18px 20px; overflow-x: auto; font-size: 14px; line-height: 1.6; }
code { font-family: var(--mono); }
p code, li code, td code { background: var(--accent-soft); color: var(--accent-dark); padding: 2px 7px; border-radius: 6px; font-size: .88em; }
pre code { background: none; color: #e2e8f0; padding: 0; }
table { width: 100%; border-collapse: collapse; margin: 20px 0; font-size: 15px; display: block; overflow-x: auto; }
th, td { border: 1px solid var(--border); padding: 10px 14px; text-align: left; }
th { background: var(--bg-soft); font-weight: 700; }
blockquote {
  border-left: 4px solid var(--accent); margin: 20px 0; padding: 12px 20px;
  background: var(--accent-soft); border-radius: 0 10px 10px 0; color: var(--text);
}
.callout { border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: 10px; padding: 14px 18px; margin: 22px 0; background: #fff; }
.callout.warn { border-left-color: #d97706; background: #fffbeb; }
.callout-title { font-weight: 700; margin-bottom: 6px; }
.author-box {
  display: flex; gap: 16px; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px; margin: 40px 0; background: var(--bg-soft); align-items: flex-start;
}
.author-avatar {
  width: 56px; height: 56px; border-radius: 50%; background: var(--accent); color: #fff;
  display: flex; align-items: center; justify-content: center; font-weight: 800; font-size: 22px; flex-shrink: 0;
}
.author-box p { margin: 4px 0 0; font-size: 15px; color: var(--muted); }
.tags { margin: 24px 0; }
.tag {
  display: inline-block; background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: 999px; padding: 4px 14px; font-size: 13px; margin: 0 8px 8px 0; color: var(--muted);
}
.tag:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }
.pager { display: flex; justify-content: space-between; gap: 16px; margin: 40px 0 0; }
.pager a { border: 1px solid var(--border); border-radius: 10px; padding: 14px 18px; flex: 1; color: var(--text); font-size: 15px; }
.pager a:hover { border-color: var(--accent); text-decoration: none; }
.pager .next { text-align: right; }
.faq-item { border: 1px solid var(--border); border-radius: 10px; margin-bottom: 12px; padding: 16px 20px; }
.faq-item h3 { margin: 0 0 8px; font-size: 18px; }
.faq-item p { margin: 0; }

/* list pages */
.list-head { max-width: var(--contentw); margin-bottom: 28px; }
.list-head h1 { font-size: 34px; letter-spacing: -.6px; margin: 0 0 10px; }
.list-head p { color: var(--muted); margin: 0; }
.pagination { display: flex; gap: 10px; margin-top: 32px; justify-content: center; }
.pagination a, .pagination span { border: 1px solid var(--border); border-radius: 8px; padding: 8px 16px; font-size: 15px; }
.pagination .current { background: var(--accent); color: #fff; border-color: var(--accent); }

/* footer */
.site-footer { border-top: 1px solid var(--border); background: var(--bg-soft); margin-top: 64px; }
.footer-inner { max-width: var(--maxw); margin: 0 auto; padding: 48px 20px 32px; display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 32px; }
.footer-inner h4 { margin: 0 0 12px; font-size: 15px; }
.footer-inner p, .footer-inner a { font-size: 14px; color: var(--muted); }
.footer-inner ul { list-style: none; margin: 0; padding: 0; }
.footer-inner li { margin-bottom: 8px; }
.footer-bottom { max-width: var(--maxw); margin: 0 auto; padding: 20px; border-top: 1px solid var(--border); font-size: 13px; color: var(--muted); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; }

/* page (about/contact/privacy) */
.page h1 { font-size: 34px; letter-spacing: -.6px; }
.page { max-width: var(--contentw); margin: 0 auto; }
.page h2 { font-size: 24px; margin: 36px 0 12px; }

@media (max-width: 760px) {
  .hero h1 { font-size: 32px; }
  .article h1 { font-size: 29px; }
  .footer-inner { grid-template-columns: 1fr; }
  .nav a { margin-left: 14px; }
  .btn-ghost { margin-left: 0; margin-top: 12px; }
}