:root,
[data-theme="light"] {
  --bg: #f6f8fa;
  --panel: #ffffff;
  --text: #1f2328;
  --muted: #636c76;
  --border: #d0d7de;
  --link: #1a56db;
  --linkHover: #1240ab;
  --codeBg: #0f172a;
  --header-bg: rgba(255,255,255,0.85);
  --nav-btn-bg: rgba(240,242,244,0.8);
  --nav-btn-active-border: rgba(26,86,219,0.5);
  --nav-btn-active-bg: rgba(26,86,219,0.06);
}

[data-theme="dark"] {
  --bg: #0b0f19;
  --panel: #111827;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --border: #1f2937;
  --link: #93c5fd;
  --linkHover: #bfdbfe;
  --codeBg: #0b1220;
  --header-bg: rgba(17,24,39,0.6);
  --nav-btn-bg: rgba(11,15,25,0.5);
  --nav-btn-active-border: rgba(147,197,253,0.6);
  --nav-btn-active-bg: rgba(147,197,253,0.08);
}

/* Theme toggle button */
.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  cursor: pointer;
  border-radius: 8px;
  padding: 4px 10px;
  font-size: 14px;
  line-height: 1;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
}
.theme-toggle:hover { background: var(--nav-btn-bg); color: var(--text); }

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji";
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

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

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 24px;
}

.header {
  border-bottom: 1px solid var(--border);
  background: var(--header-bg);
  backdrop-filter: blur(6px);
}

.brand {
  display: flex;
  gap: 12px;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
}

.brand h1 {
  font-size: 18px;
  margin: 0;
  letter-spacing: 0.2px;
}

.brand .tagline {
  color: var(--muted);
  font-size: 13px;
}

.nav {
  margin-top: 14px;
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.nav a {
  display: inline-block;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--nav-btn-bg);
  font-size: 13px;
}

.nav a.active {
  border-color: var(--nav-btn-active-border);
  background: var(--nav-btn-active-bg);
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
}

.grid {
  display: grid;
  gap: 16px;
}

@media (min-width: 900px) {
  .grid.cols-2 { grid-template-columns: 1fr 1fr; }
}

h2 { margin: 22px 0 8px; font-size: 18px; }
h3 { margin: 18px 0 6px; font-size: 15px; color: #f3f4f6; }
p { margin: 10px 0; }
ul { margin: 10px 0 10px 18px; }
li { margin: 6px 0; }

.kv {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 10px 14px;
  font-size: 14px;
}

.kv .k { color: var(--muted); }

hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 20px 0;
}

code, pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
}

pre {
  background: var(--codeBg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px;
  overflow: auto;
}

.note {
  border-left: 4px solid rgba(147, 197, 253, 0.6);
  padding: 10px 12px;
  background: rgba(147, 197, 253, 0.06);
  border-radius: 10px;
}

.footer {
  margin-top: 30px;
  color: var(--muted);
  font-size: 12px;
  border-top: 1px solid var(--border);
  padding-top: 16px;
}

.small { color: var(--muted); font-size: 13px; }

/* Mermaid: keep it readable on dark background */
.mermaid {
  background: #0b1220;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px;
}