:root {
  --bg: #f6f8f8; --surface: #ffffff; --text: #15191e; --muted: #5b6672;
  --line: #dde3ea; --accent: #1f6f6b; --accent-ink: #ffffff;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0e1214; --surface: #161c1f; --text: #eef1f4; --muted: #9aa3ad; --line: #263035; --accent: #7fd6cf; --accent-ink: #062320; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text);
  font: 17px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
main { max-width: 760px; margin: 0 auto; padding: 32px 16px 64px; }
header { display: flex; align-items: center; gap: 12px; margin-bottom: 24px; }
.mark { width: 44px; height: 44px; border-radius: 12px; background: #1f6f6b; display: grid; place-items: center; color: #fff; font-weight: 700; }
header a { color: inherit; text-decoration: none; font-weight: 700; font-size: 20px; }
h1 { font-size: clamp(28px, 6vw, 38px); line-height: 1.2; margin: 0 0 8px; }
h2 { font-size: 21px; margin: 32px 0 8px; }
p, li { max-width: 68ch; }
a { color: var(--accent); }
.muted { color: var(--muted); }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 18px 20px; margin: 16px 0; }
ol li, ul li { margin: 6px 0; }
.btn { display: inline-block; background: var(--accent); color: var(--accent-ink); padding: 12px 20px; border-radius: 12px; text-decoration: none; font-weight: 600; }
footer { margin-top: 48px; padding-top: 16px; border-top: 1px solid var(--line); font-size: 15px; color: var(--muted); }
footer a { margin-right: 14px; }