/* ── Variables ─────────────────────────────────────────────── */
:root {
  --purple: #7c3aed;
  --purple-light: #ede9fe;
  --purple-mid: #a78bfa;
  --bg: #f8f7ff;
  --surface: #ffffff;
  --border: #e2e0f0;
  --text: #1e1b4b;
  --text-muted: #6b7280;
  --code-bg: #282a36;
  --radius: 8px;
  --sidebar-w: 220px;
  --font: system-ui, -apple-system, sans-serif;
  --mono: "Cascadia Code", "Fira Code", "Consolas", monospace;
}

/* ── Dark theme ────────────────────────────────────────────── */
[data-theme="dark"] {
  --purple: #a78bfa;
  --purple-light: #2a1f4a;
  --purple-mid: #7c3aed;
  --bg: #0f0d1a;
  --surface: #1a1730;
  --border: #2d2a45;
  --text: #e8e4ff;
  --text-muted: #9990cc;
  --code-bg: #0d0b18;
}

/* show/hide the right icon per theme */
[data-theme="dark"]  .icon-sun  { display: none; }
[data-theme="light"] .icon-moon { display: none; }
/* default before JS runs: hide both, avoid flash */
html:not([data-theme]) .icon-sun  { display: none; }
html:not([data-theme]) .icon-moon { display: none; }

/* ── Reset ─────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ── Header ────────────────────────────────────────────────── */
.site-header {
  background: var(--purple);
  color: #fff;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: baseline;
  gap: 1rem;
  position: sticky;
  top: 0;
  z-index: 10;
  box-shadow: 0 2px 8px rgba(124,58,237,0.25);
}

.site-title {
  color: #fff;
  text-decoration: none;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.site-tagline {
  font-size: 0.8rem;
  opacity: 0.65;
  flex: 1;
}

.theme-toggle {
  background: none;
  border: 1.5px solid rgba(255,255,255,0.35);
  border-radius: 6px;
  color: #fff;
  cursor: pointer;
  padding: 4px 7px;
  display: flex;
  align-items: center;
  transition: border-color 0.15s, background 0.15s;
}

.theme-toggle:hover {
  background: rgba(255,255,255,0.12);
  border-color: rgba(255,255,255,0.6);
}

/* ── Layout ────────────────────────────────────────────────── */
.layout {
  display: flex;
  flex: 1;
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
  padding: 2rem 1rem;
  gap: 2rem;
}

/* ── Sidebar ───────────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
}

.nav-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.sidebar ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.sidebar a {
  display: block;
  padding: 0.45rem 0.75rem;
  border-radius: var(--radius);
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  transition: background 0.15s, color 0.15s;
}

.sidebar a:hover { background: var(--purple-light); color: var(--purple); }
.sidebar a.active {
  background: var(--purple);
  color: #fff;
  font-weight: 600;
}

/* ── Content ───────────────────────────────────────────────── */
.content {
  flex: 1;
  min-width: 0;
}

/* ── Topic page ────────────────────────────────────────────── */
.topic h1 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  color: var(--purple);
  letter-spacing: -0.02em;
}

.lead {
  font-size: 1.1rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  border-left: 3px solid var(--purple-mid);
  padding-left: 0.75rem;
}

.topic-body h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin: 2.5rem 0 0.75rem;
  color: var(--text);
  border-bottom: 2px solid var(--border);
  padding-bottom: 0.35rem;
}

.topic-body h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
  color: var(--purple);
}

.topic-body p { margin-bottom: 0.9rem; }

.topic-body ul, .topic-body ol {
  padding-left: 1.4rem;
  margin-bottom: 0.9rem;
}

.topic-body li { margin-bottom: 0.3rem; }

.topic-body code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: var(--purple-light);
  color: var(--purple);
  padding: 0.1em 0.35em;
  border-radius: 4px;
}

.topic-body pre code {
  background: none;
  color: inherit;
  padding: 0;
}

/* Hugo syntax highlight wraps in <div class="highlight"><pre>...</pre></div> */
.topic-body .highlight, .demo-source .highlight {
  border-radius: var(--radius);
  overflow: auto;
  margin: 0.75rem 0;
}

.topic-body .highlight pre {
  padding: 1rem;
  font-size: 0.85rem;
  line-height: 1.5;
  font-family: var(--mono);
}

/* ── Demo block ────────────────────────────────────────────── */
.demo-block {
  border: 2px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 1rem 0 1.75rem;
  background: var(--surface);
}

.demo-preview {
  padding: 0;
  background: var(--surface);
}

.demo-iframe {
  width: 100%;
  display: block;
  border: none;
}

.demo-source {
  border-top: 2px solid var(--border);
}

.demo-source summary {
  padding: 0.5rem 1rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  user-select: none;
  background: var(--bg);
  letter-spacing: 0.02em;
}

.demo-source summary:hover { color: var(--purple); }

.demo-source[open] summary { border-bottom: 1px solid var(--border); }

.demo-source .highlight {
  margin: 0;
  border-radius: 0;
}

.demo-source .highlight pre {
  padding: 1rem;
  font-size: 0.82rem;
  font-family: var(--mono);
  line-height: 1.5;
}

/* ── Home page ─────────────────────────────────────────────── */
.home-hero {
  margin-bottom: 2.5rem;
}

.home-hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--purple);
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
}

.home-hero p { font-size: 1.1rem; color: var(--text-muted); }

.topic-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: 1.25rem;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
}

.card:hover {
  border-color: var(--purple);
  box-shadow: 0 4px 16px rgba(124,58,237,0.12);
  transform: translateY(-2px);
}

.card-icon { font-size: 1.5rem; }

.card strong { font-size: 1rem; font-weight: 700; }

.card span:last-child { font-size: 0.82rem; color: var(--text-muted); }

/* ── Footer ────────────────────────────────────────────────── */
.site-footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  background: var(--surface);
}

.site-footer a {
  color: var(--purple);
  text-decoration: none;
}

.site-footer a:hover { text-decoration: underline; }

/* ── Icons ─────────────────────────────────────────────────── */
.icon {
  display: inline-block;
  width: 1em;
  height: 1em;
  fill: currentColor;
  vertical-align: middle;
  flex-shrink: 0;
}

.card-icon .icon {
  width: 1.6rem;
  height: 1.6rem;
  color: var(--purple);
}

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 680px) {
  .layout { flex-direction: column; padding: 1rem; gap: 1rem; }
  .sidebar { width: 100%; }
  .sidebar ul { flex-direction: row; flex-wrap: wrap; }
}