:root { --bg: #f6f8f8; --fg: #1d2b2e; --muted: #5d6f73; --accent: #1b7f80; --card: #ffffff; --line: #dde5e6; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #111819; --fg: #e6eeef; --muted: #9db0b3; --accent: #5cc6c4; --card: #1a2324; --line: #2b3a3c; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 16px/1.75 -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", sans-serif; }
main { max-width: 720px; margin: 0 auto; padding: 32px 16px 64px; }
header { display: flex; align-items: center; gap: 14px; margin-bottom: 24px; }
header img { width: 56px; height: 56px; border-radius: 13px; }
h1 { font-size: 1.6rem; margin: 0; }
h2 { font-size: 1.15rem; margin: 2em 0 .4em; }
p, li { color: var(--fg); }
.muted { color: var(--muted); font-size: .9rem; }
nav { display: flex; gap: 16px; flex-wrap: wrap; margin: 8px 0 24px; }
a { color: var(--accent); }
section.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 4px 20px 16px; margin-top: 24px; }
hr { border: 0; border-top: 1px solid var(--line); margin: 40px 0; }