:root {
  --bg: #f4f6f9;
  --panel: #ffffff;
  --ink: #1e2530;
  --muted: #5b6675;
  --line: #e1e6ee;
  --brand: #1f6feb;
  --brand-2: #0b4fa8;
  --accent: #e8513a;
  --shadow: 0 1px 3px rgba(20,30,50,.08), 0 6px 20px rgba(20,30,50,.06);
  --radius: 12px;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", "Noto Sans", "Microsoft YaHei", "Hiragino Sans", "Malgun Gothic", sans-serif;
  background: var(--bg); color: var(--ink); line-height: 1.5;
}
a { color: var(--brand); text-decoration: none; }

/* Top bar */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 12px;
  background: linear-gradient(90deg, var(--brand-2), var(--brand));
  color: #fff; padding: 10px 16px;
  box-shadow: var(--shadow);
}
.topbar .brand { font-weight: 700; font-size: 16px; letter-spacing: .3px; margin-right: auto; display:flex; align-items:center; gap:8px; }
.topbar .brand .dot { width: 10px; height: 10px; border-radius: 50%; background: #fff; opacity:.9; }
.topbar a.btn, .topbar .lang-wrap { color: #fff; }
.topbar a.btn {
  background: rgba(255,255,255,.14); border: 1px solid rgba(255,255,255,.35);
  padding: 6px 12px; border-radius: 8px; font-size: 13px; font-weight: 600;
  display: inline-flex; align-items: center; gap: 6px; transition: background .15s;
}
.topbar a.btn:hover { background: rgba(255,255,255,.26); }
.lang-wrap { display: inline-flex; align-items: center; gap: 6px; font-size: 13px; }
.lang-wrap select {
  background: rgba(255,255,255,.16); color: #fff; border: 1px solid rgba(255,255,255,.35);
  border-radius: 8px; padding: 5px 8px; font-size: 13px; outline: none;
}
.lang-wrap select option { color: #1e2530; }

/* Layout */
.wrap { max-width: 1080px; margin: 0 auto; padding: 24px 16px 56px; }
.page-head { margin: 8px 0 20px; }
.page-head h1 { margin: 0 0 6px; font-size: 26px; }
.page-head p { margin: 0; color: var(--muted); max-width: 760px; }

/* Hub cards */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin-top: 8px; }
.card {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px; box-shadow: var(--shadow); transition: transform .12s, box-shadow .12s;
  display: flex; flex-direction: column; gap: 8px; color: var(--ink);
}
.card:hover { transform: translateY(-3px); box-shadow: 0 10px 28px rgba(20,30,50,.12); }
.card .ico { width: 42px; height: 42px; border-radius: 10px; background: var(--brand); color:#fff;
  display: flex; align-items: center; justify-content: center; font-size: 20px; }
.card h3 { margin: 4px 0 0; font-size: 18px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }
.card .go { margin-top: auto; font-weight: 600; color: var(--brand); font-size: 14px; }

/* Controls */
.controls { display: flex; flex-wrap: wrap; gap: 14px; align-items: flex-end;
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px; box-shadow: var(--shadow); margin-bottom: 20px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: 12px; font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: .4px; }
.field select { min-width: 200px; padding: 9px 10px; border: 1px solid var(--line); border-radius: 8px; font-size: 14px; background:#fff; color: var(--ink); }
button.primary {
  background: var(--brand); color: #fff; border: none; border-radius: 8px;
  padding: 10px 18px; font-size: 14px; font-weight: 600; cursor: pointer;
}
button.primary:hover { background: var(--brand-2); }
button.secondary {
  background: #fff; color: var(--brand); border: 1px solid var(--brand);
  border-radius: 8px; padding: 10px 18px; font-size: 14px; font-weight: 600; cursor: pointer;
}
button.secondary:hover { background: #eef5ff; }

/* Result / tables */
.note { color: var(--muted); font-size: 13px; margin: 4px 0 14px; }
.panel { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 0; overflow: hidden; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
thead th { background: #eef3fb; color: #36465c; text-align: left; padding: 10px 12px;
  border-bottom: 2px solid var(--line); font-weight: 700; white-space: nowrap; }
tbody td { padding: 9px 12px; border-bottom: 1px solid var(--line); }
tbody tr:nth-child(even) { background: #fafbfd; }
tbody tr:hover { background: #eef5ff; }
.code { font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace; }
.empty { padding: 28px; text-align: center; color: var(--muted); }
.empty-hint { padding: 0 28px 22px; text-align: center; color: var(--muted); font-size: 13px; opacity: .8; }

/* two-col ref */
.ref-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px,1fr)); gap: 16px; }
.ref { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); padding: 16px 18px; }
.ref h3 { margin: 0 0 10px; font-size: 16px; }
.code-table td:first-child { font-family: monospace; font-weight: 700; color: var(--brand-2); }

footer.global { text-align: center; color: var(--muted); font-size: 12px; padding: 22px 16px 40px; }

/* Illustrations */
.ill-card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 16px 18px; margin-bottom: 18px; overflow-x: auto; }
.ill-title { font-size: 14px; font-weight: 700; color: var(--brand-2); margin-bottom: 10px; }
.ill { width: 100%; }
.ill-svg { display: block; margin: 0 auto; }
.ill-legend { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; margin-top: 10px;
  font-size: 12px; color: var(--muted); }
.ill-legend .sw { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 5px; vertical-align: -1px; }
.ill-legend .sw-a { background: var(--brand); }
.ill-legend .sw-b { background: var(--accent); }

@media (max-width: 560px) {
  .controls { flex-direction: column; align-items: stretch; }
  .field select { min-width: 0; width: 100%; }
  .topbar { flex-wrap: wrap; }
  .topbar .brand { margin-right: auto; }
  .ill-card { padding: 12px; }
}