:root { --bg: #fff; --text: #1d1d1f; --muted: #6e6e73; --line: #d2d2d7; --link: #0066cc; --panel: #f5f5f7; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #000; --text: #f5f5f7; --muted: #a1a1a6; --line: #424245; --link: #2997ff; --panel: #1c1c1e; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); line-height: 1.8; font-size: 16px;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif; }
header, main, footer { max-width: 720px; margin: 0 auto; padding: 0 16px; }
header { padding-top: 20px; font-size: 14px; }
header a { color: var(--muted); text-decoration: none; }
footer { padding-top: 24px; padding-bottom: 40px; font-size: 14px; color: var(--muted); border-top: 1px solid var(--line); margin-top: 48px; }
a { color: var(--link); }
h1 { font-size: 28px; line-height: 1.4; margin: 24px 0 8px; }
h2 { font-size: 20px; margin: 36px 0 8px; }
h3 { font-size: 17px; margin: 24px 0 4px; }
.lead, .note { color: var(--muted); font-size: 14px; }
.posts { list-style: none; padding: 0; }
.posts li { margin: 20px 0; }
.posts a { font-size: 18px; font-weight: 600; }
.posts p { margin: 2px 0 0; }
.pr { font-size: 13px; border: 1px solid var(--text); color: var(--text); border-radius: 3px; padding: 0 4px; margin-left: 4px; vertical-align: middle; }
figure { margin: 20px 0; }
img { max-width: 100%; height: auto; }
.ai { margin: 12px 0 24px; padding: 12px 16px; background: var(--panel); border-radius: 8px; font-size: 14px; }