:root {
  --bg: #ffffff; --fg: #1a1a1a; --muted: #595959; --accent: #2563eb;
  --border: #e5e5e5; --code-bg: #f5f5f7;
  --error-fg: #991b1b; --error-bg: #fee2e2;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f0f10; --fg: #e8e8e8; --muted: #b8b8b8; --accent: #60a5fa; --border: #2a2a2a; --code-bg: #1a1a1c;
          --error-fg: #fca5a5; --error-bg: #450a0a; }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

/* Accessibility: visible focus + skip link + reduced motion */
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 3px; }
.skip-link {
  position: absolute; left: -9999px; top: 8px;
  padding: 8px 14px; background: var(--accent); color: #fff;
  text-decoration: none; border-radius: 6px; font-weight: 500; z-index: 1000;
}
.skip-link:focus, .skip-link:focus-visible { left: 8px; outline: 2px solid var(--fg); outline-offset: 2px; }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
  }
}
body {
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  background: var(--bg); color: var(--fg);
  max-width: 720px; margin: 0 auto; padding: 48px 24px;
}
header { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 48px; padding-bottom: 16px; border-bottom: 1px solid var(--border); }
header h1 { margin: 0; font-size: 18px; }
header nav a { color: var(--muted); text-decoration: none; margin-left: 16px; font-size: 14px; }
header nav a:hover { color: var(--fg); }
a { color: var(--accent); }
article h1 { font-size: 28px; margin-top: 0; }
article .meta { color: var(--muted); font-size: 14px; margin-bottom: 32px; }
article .meta .badge { display: inline-block; padding: 2px 8px; border: 1px solid var(--border); border-radius: 999px; margin-right: 8px; font-size: 12px; }
.post-list { list-style: none; padding: 0; }
.post-list li { padding: 16px 0; border-bottom: 1px solid var(--border); }
.post-list h2 { margin: 0 0 4px 0; font-size: 18px; }
.post-list h2 a { color: var(--fg); text-decoration: none; }
.post-list h2 a:hover { color: var(--accent); }
.post-list .summary { margin: 4px 0 0 0; color: var(--muted); font-size: 14px; }
.post-list .meta { color: var(--muted); font-size: 12px; margin-top: 4px; }
pre { background: var(--code-bg); padding: 16px; overflow: auto; border-radius: 6px; font-size: 13px; }
code { background: var(--code-bg); padding: 2px 5px; border-radius: 3px; font-size: 0.9em; font-family: ui-monospace, SF Mono, Menlo, monospace; }
pre code { background: none; padding: 0; font-size: 13px; }
blockquote { border-left: 3px solid var(--border); margin: 0; padding: 4px 16px; color: var(--muted); }
.opennote-broken-link { color: var(--muted); text-decoration: line-through dotted; cursor: help; }
.shiki { padding: 16px; border-radius: 6px; overflow: auto; font-size: 13px; }
.shiki code { background: none; padding: 0; }
@media (prefers-color-scheme: dark) {
  .shiki, .shiki span { color: var(--shiki-dark) !important; background-color: var(--shiki-dark-bg) !important; }
}
@media (prefers-color-scheme: light) {
  .shiki, .shiki span { color: var(--shiki-light) !important; background-color: var(--shiki-light-bg) !important; }
}
.mermaid { text-align: center; margin: 16px 0; }
.opennote-math-error { color: var(--error-fg); background: var(--error-bg); padding: 2px 6px; border-radius: 3px; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 4px 0; }
footer { margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--border); color: var(--muted); font-size: 13px; }