:root {
  --bg: #f5f7fb;
  --card: #ffffff;
  --ink: #0f172a;
  --muted: #475569;
  --line: rgba(15, 23, 42, 0.08);
  --violet: #7c3aed;
  --violet-deep: #6d28d9;
  --pink: #ec4899;
  --soft: #f1eefc;
  --chip: #ede9fe;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Sarabun", system-ui, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, rgba(124, 58, 237, 0.12), transparent 60%),
    radial-gradient(900px 400px at 100% 0%, rgba(236, 72, 153, 0.08), transparent 55%),
    var(--bg);
  line-height: 1.7;
}
a { color: var(--violet-deep); text-decoration: none; }
a:hover { text-decoration: underline; }
.topbar {
  position: sticky; top: 0; z-index: 20;
  backdrop-filter: blur(12px);
  background: rgba(255,255,255,0.88);
  border-bottom: 1px solid var(--line);
}
.topbar-inner {
  max-width: 960px; margin: 0 auto;
  padding: 0.85rem 1.25rem;
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
}
.brand {
  display: flex; align-items: center; gap: 0.65rem;
  font-family: "Kanit", sans-serif; font-weight: 600; color: var(--ink);
  text-decoration: none;
}
.brand-mark {
  width: 34px; height: 34px; border-radius: 10px;
  background: linear-gradient(135deg, var(--violet), var(--pink));
  color: #fff; display: grid; place-items: center;
  font-size: 0.75rem; font-weight: 700;
}
.top-links { display: flex; gap: 0.75rem; flex-wrap: wrap; font-size: 0.92rem; }
.top-links a {
  color: var(--muted); text-decoration: none;
  padding: 0.35rem 0.65rem; border-radius: 999px;
}
.top-links a:hover { background: var(--soft); color: var(--violet-deep); }
.hero { max-width: 960px; margin: 0 auto; padding: 2.25rem 1.25rem 1rem; }
.hero h1 {
  font-family: "Kanit", sans-serif;
  font-size: clamp(1.6rem, 3vw, 2.15rem);
  margin: 0 0 0.5rem;
}
.hero .lead { color: var(--muted); margin: 0 0 1rem; max-width: 46rem; }
.meta { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.25rem; }
.chip {
  display: inline-flex; align-items: center;
  background: var(--chip); color: var(--violet-deep);
  border: 1px solid rgba(124, 58, 237, 0.15);
  border-radius: 999px; padding: 0.28rem 0.75rem;
  font-size: 0.85rem; font-weight: 500;
}
.layout {
  max-width: 960px; margin: 0 auto;
  padding: 0 1.25rem 3.5rem;
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 1.5rem;
}
@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .toc { position: static !important; }
}
.toc {
  position: sticky; top: 72px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1rem;
}
.toc h2 { font-family: "Kanit", sans-serif; font-size: 0.95rem; margin: 0 0 0.65rem; }
.toc nav { display: flex; flex-direction: column; gap: 0.28rem; }
.toc a {
  color: var(--muted); text-decoration: none;
  font-size: 0.88rem; padding: 0.28rem 0.45rem; border-radius: 8px;
}
.toc a:hover { background: var(--soft); color: var(--violet-deep); }
.content {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 1.5rem 1.5rem 2rem;
}
.content section {
  padding: 0.35rem 0 1.35rem;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 88px;
}
.content section:last-child { border-bottom: 0; padding-bottom: 0; }
.content h2 {
  font-family: "Kanit", sans-serif;
  font-size: 1.2rem; margin: 0.4rem 0 0.7rem;
}
.content p, .content li { color: #1e293b; font-size: 0.98rem; }
.content ul { padding-left: 1.25rem; margin: 0.4rem 0 0.8rem; }
.content li { margin: 0.28rem 0; }
.callout {
  background: linear-gradient(135deg, rgba(124,58,237,0.07), rgba(236,72,153,0.05));
  border: 1px solid rgba(124, 58, 237, 0.18);
  border-radius: 14px;
  padding: 1rem 1.1rem;
  margin: 0.85rem 0;
}
.note {
  font-size: 0.9rem; color: var(--muted);
  background: #f8fafc; border-left: 3px solid var(--violet);
  padding: 0.65rem 0.85rem; border-radius: 0 10px 10px 0;
  margin: 0.75rem 0;
}
.footer {
  max-width: 960px; margin: 0 auto;
  padding: 0 1.25rem 2.5rem;
  color: var(--muted); font-size: 0.88rem;
}
.footer-card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: 14px; padding: 1rem 1.15rem;
}