:root {
  --bg: #0e1117;
  --card: #161b22;
  --card-border: #2b313a;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #58a6ff;
  --warn: #f0b429;
  --danger: #ff7b72;
  --ok: #3fb950;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.hero {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.25rem 1rem;
  text-align: center;
}

.banner {
  background: rgba(240, 180, 41, 0.12);
  border: 1px solid var(--warn);
  color: var(--text);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
  font-size: 0.95rem;
  text-align: left;
  margin-bottom: 1.5rem;
}

h1 {
  font-size: clamp(1.8rem, 5vw, 2.6rem);
  margin: 0.5rem 0;
}

.subtitle { color: var(--muted); font-size: 1.1rem; max-width: 620px; margin: 0.5rem auto; }

main { max-width: 1100px; margin: 0 auto; padding: 1rem 1.25rem 3rem; }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 1.25rem 1.4rem;
}

.card h2 { margin-top: 0; font-size: 1.15rem; }

.myth { border-color: var(--danger); background: rgba(255, 123, 114, 0.08); margin-top: 1.5rem; }
.myth u { text-decoration-color: var(--danger); }

.muted { color: var(--muted); font-size: 0.9rem; }

dl { margin: 0.75rem 0 0; display: grid; grid-template-columns: max-content 1fr; gap: 0.35rem 1rem; }
dt { color: var(--muted); font-weight: 600; font-size: 0.85rem; }
dd { margin: 0; word-break: break-word; font-variant-numeric: tabular-nums; }
dd.highlight { color: var(--accent); font-weight: 600; }

button {
  background: var(--accent);
  color: #06101f;
  border: none;
  border-radius: 8px;
  padding: 0.6rem 1.1rem;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  margin-top: 0.5rem;
}
button:hover { filter: brightness(1.1); }
button:disabled { opacity: 0.5; cursor: default; }

.lessons { margin-top: 1.5rem; border-color: var(--ok); }
.lessons li { margin: 0.4rem 0; }

footer { text-align: center; color: var(--muted); padding: 2rem 1rem; font-size: 0.85rem; }

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f8fa; --card: #ffffff; --card-border: #d0d7de;
    --text: #1f2328; --muted: #656d76; --accent: #0969da;
  }
  button { color: #fff; }
}