:root {
  --bg: #f2f2f7;
  --card: #ffffff;
  --ink: #1c1c1e;
  --muted: #6c6c70;
  --accent: #0a7c66;
  --line: #e5e5ea;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --card: #1c1c1e;
    --ink: #f2f2f7;
    --muted: #98989f;
    --accent: #3dd6b0;
    --line: #38383a;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}
header, main, footer { max-width: 720px; margin: 0 auto; padding: 0 16px; }
header {
  display: flex; flex-wrap: wrap; gap: 8px 16px; align-items: center; justify-content: space-between;
  padding-top: 20px; padding-bottom: 12px;
}
.brand { font-weight: 700; font-size: 20px; color: var(--accent); text-decoration: none; }
nav { display: flex; gap: 16px; }
nav a { color: var(--muted); text-decoration: none; }
nav a[aria-current="page"] { color: var(--ink); font-weight: 600; }
article { background: var(--card); border-radius: 16px; padding: 24px 20px; }
h1 { font-size: 28px; line-height: 1.25; margin: 0 0 4px; }
h2 { font-size: 20px; margin: 32px 0 8px; padding-top: 16px; border-top: 1px solid var(--line); }
h3 { font-size: 17px; margin: 20px 0 4px; }
.meta { color: var(--muted); font-size: 15px; margin-top: 0; }
a { color: var(--accent); }
ul { padding-left: 22px; }
li + li { margin-top: 4px; }
footer { color: var(--muted); font-size: 14px; padding-top: 8px; padding-bottom: 32px; }
@media (min-width: 768px) {
  article { padding: 40px 48px; }
  h1 { font-size: 34px; }
}