:root {
  --bg: #ffffff;
  --fg: #0a0a0a;
  --muted: #6b7280;
  --card: #f5f5f5;
  --line: #e5e7eb;
  --primary: #111111;
  --focus: #111111;
  color-scheme: light;
}
:root.dark {
  --bg: #0f0f10;
  --fg: #f5f5f5;
  --muted: #a1a1aa;
  --card: #1a1a1b;
  --line: #2a2a2b;
  --primary: #f5f5f5;
  --focus: #ffffff;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font-family: "Noto Sans", system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  line-height: 1.6;
}
.sr-only { position: absolute; width:1px; height:1px; padding:0; margin:-1px; overflow:hidden; clip:rect(0,0,0,0); border:0; }
a { color: inherit; text-decoration: none; }
a:focus-visible, button:focus-visible, input:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; border-radius: 6px; }
.site-header {
  position: sticky; top:0; z-index: 50; backdrop-filter: saturate(1.2) blur(8px);
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  border-bottom: 1px solid var(--line); display: flex; align-items: center; gap: 12px; padding: 10px 16px;
}
.brand { display:flex; align-items:center; gap:10px; font-weight:700; }
.nav { margin-left: auto; display:flex; align-items:center; gap:12px; }
.menu { list-style:none; display:flex; gap:8px; margin:0; padding:0; }
.menu a { padding:8px 10px; border-radius: 8px; }
.menu a:hover { background: var(--card); }
.menu .cta { border:1px solid var(--fg); }
.nav-toggle { display:none; background:none; border:1px solid var(--line); border-radius:8px; padding:6px; }
.theme-toggle { background:none; border:1px solid var(--line); border-radius:8px; padding:6px; display:flex; align-items:center; gap:6px; }
.theme-toggle .icon-moon { display:none; }
:root.dark .theme-toggle .icon-sun { display:none; }
:root.dark .theme-toggle .icon-moon { display:block; }

main { max-width: 1100px; margin: 0 auto; padding: 0 16px; }
.section { padding: 56px 0; }
.hero { padding: 72px 0 48px; border-bottom:1px solid var(--line); }
.hero-inner { display:grid; gap:18px; }
.lead { color: var(--muted); max-width: 70ch; }
.hero-actions { display:flex; gap:10px; }
.btn { display:inline-block; padding:10px 14px; border:1px solid var(--fg); border-radius:10px; transition: transform .08s ease, background .2s ease; }
.btn:hover { transform: translateY(-1px); background: var(--card); }
.btn.primary { background: var(--fg); color: var(--bg); border-color: var(--fg); }
.hero-grid { display:grid; grid-template-columns: repeat(8, minmax(0, 1fr)); gap:8px; opacity:.9; }
.hero-grid .chip { border:1px dashed var(--line); padding:8px; border-radius:10px; text-align:center; font-size:14px; color: var(--muted); }

.content h2 { margin: 0 0 8px 0; }
.content p { margin-top:0; color: var(--muted); }
.cards { display:grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap:12px; margin-top: 12px; }
.card { background: var(--card); border:1px solid var(--line); border-radius:12px; padding:16px; }
.card h3 { margin-top:0; }
.grid2 { display:grid; grid-template-columns: 1.1fr .9fr; gap:12px; align-items:start; }
.grid3 { display:grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap:12px; }
.list { padding-left: 18px; }
.list.tight li { margin: 4px 0; }
.mono { font-family: "Space Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

.timeline { position: relative; padding-left: 18px; }
.timeline::before { content:""; position:absolute; left:6px; top:0; bottom:0; width:2px; background: var(--line); }
.timeline .titem { position:relative; margin: 10px 0; padding-left: 8px; }
.timeline .titem::before { content:""; position:absolute; left:-12px; top:8px; width:10px; height:10px; border-radius:50%; background: var(--fg); }

.glossario { list-style:none; padding:0; margin:12px 0 0 0; }
.glossario li { border-bottom:1px solid var(--line); padding:10px 0; }
.glossario .term { font-weight: 700; }
.input { width:100%; padding:10px 12px; border:1px solid var(--line); border-radius:10px; background: var(--bg); color: var(--fg); }
.note { margin-top:10px; }
.note summary { cursor:pointer; }

.quiz { display:grid; gap:12px; }
.quiz .q { border:1px solid var(--line); border-radius:12px; padding:12px; }
.quiz .options { display:grid; gap:8px; }
.quiz button.opt { text-align:left; padding:10px; border:1px solid var(--line); background: var(--bg); border-radius:10px; cursor:pointer; }
.quiz button.opt[aria-pressed="true"] { border-color: var(--fg); background: var(--card); }
.quiz .result { padding:10px; border-radius:10px; background: var(--card); }
.quiz .controls { display:flex; gap:10px; }

.site-footer { border-top:1px solid var(--line); padding: 24px 16px; margin-top: 40px; color: var(--muted); }

@media (max-width: 960px) {
  .cards { grid-template-columns: 1fr 1fr; }
  .grid2 { grid-template-columns: 1fr; }
  .grid3 { grid-template-columns: 1fr 1fr; }
  .hero-grid { grid-template-columns: repeat(4, 1fr); }
}
@media (max-width: 720px) {
  .menu { position: fixed; inset: 56px 12px auto 12px; background: var(--bg); border:1px solid var(--line); border-radius:12px; padding:12px; display:none; flex-direction:column; gap:6px; }
  .menu.open { display:flex; }
  .nav-toggle { display:inline-flex; }
  .cards, .grid3 { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition-duration: 0.001ms !important; animation-duration: 0.001ms !important; }
}