:root {
  color-scheme: light dark;
  --ink: #17171b;
  --muted: #64646d;
  --surface: #ffffff;
  --line: #e7e7eb;
  --accent: #d71920;
  --canvas: #f7f7f8;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: var(--ink);
  background: var(--canvas);
}

main { max-width: 800px; margin: 0 auto; padding: 48px 24px 64px; }

header {
  border-bottom: 1px solid var(--line);
  background: #101015;
  color: #fff;
}

.header-inner { max-width: 800px; margin: 0 auto; padding: 18px 24px; }
.brand { font-size: 18px; font-weight: 750; letter-spacing: .01em; }
.brand span { color: #ff5e63; }

nav { margin-top: 8px; display: flex; flex-wrap: wrap; gap: 14px; }
nav a { color: #fff; font-size: 14px; text-decoration: none; opacity: .88; }
nav a:hover, nav a:focus { opacity: 1; text-decoration: underline; }

article { padding: 32px; background: var(--surface); border: 1px solid var(--line); border-radius: 16px; }
h1 { line-height: 1.18; margin: 0 0 8px; font-size: clamp(30px, 6vw, 42px); }
h2 { margin-top: 36px; line-height: 1.25; font-size: 22px; }
h3 { margin-top: 24px; font-size: 17px; }
p, li { font-size: 16px; }
.meta { color: var(--muted); margin-top: 0; }
.notice { padding: 14px 16px; border-left: 4px solid var(--accent); background: #fff1f1; }
.contact { padding: 16px; border-radius: 12px; background: #f4f4f6; }
a { color: #ad1017; }
footer { padding-top: 20px; color: var(--muted); font-size: 14px; }

@media (prefers-color-scheme: dark) {
  :root { --ink: #f5f5f7; --muted: #b0b0ba; --surface: #1c1c22; --line: #32323a; --canvas: #101015; }
  .notice { background: #3a1d20; }
  .contact { background: #26262e; }
  a { color: #ff8085; }
}

@media (max-width: 600px) {
  main { padding: 20px 14px 40px; }
  .header-inner { padding: 14px 16px; }
  article { padding: 20px 16px; border-radius: 12px; }
  h1 { font-size: 26px; }
  h2 { font-size: 19px; margin-top: 26px; }
  p, li { font-size: 14.5px; }
}