/* === Reset & Base === */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --bg: #ffffff;
  --fg: #1a1a2e;
  --muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --border: #e2e8f0;
  --surface: #f8fafc;
  --code-bg: #f1f5f9;
  --max-w: 740px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "SF Mono", "Fira Code", "Fira Mono", Menlo, monospace;
}

/* === Typography === */
html { font-size: 17px; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.75;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.25rem;
}

h1 { font-size: 1.9rem; line-height: 1.2; margin-bottom: 0.5rem; letter-spacing: -0.02em; }
h2 { font-size: 1.45rem; line-height: 1.3; margin: 2.5rem 0 0.75rem; letter-spacing: -0.01em; }
h3 { font-size: 1.15rem; line-height: 1.4; margin: 2rem 0 0.5rem; }

p { margin: 1rem 0; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* === Skip link (accessibility) === */
.skip-link {
  position: absolute; left: -9999px; top: auto;
  background: var(--accent); color: #fff; padding: 0.5rem 1rem;
  z-index: 100;
}
.skip-link:focus { left: 1rem; top: 1rem; }

/* === Header === */
header[role="banner"] {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}
header[role="banner"] nav { display: flex; align-items: baseline; gap: 1rem; flex-wrap: wrap; }
.site-title { font-size: 1.2rem; font-weight: 700; color: var(--fg); text-decoration: none; }
.site-title:hover { color: var(--accent); text-decoration: none; }
.site-tagline { font-size: 0.85rem; color: var(--muted); }

/* === Article metadata === */
.meta { display: flex; gap: 1rem; color: var(--muted); font-size: 0.85rem; margin: 0.25rem 0; }
.reading-time::before { content: "·"; margin-right: 0.5rem; }
.description { color: var(--muted); font-size: 0.95rem; margin: 0.5rem 0 1.5rem; font-style: italic; }

/* === Tags === */
.tags, .tags-inline { display: flex; gap: 0.4rem; flex-wrap: wrap; margin: 0.5rem 0; }
.tags a, .tags-inline a {
  background: var(--surface); border: 1px solid var(--border);
  padding: 0.15rem 0.6rem; border-radius: 3px;
  font-size: 0.78rem; color: var(--muted); text-decoration: none;
}
.tags a:hover, .tags-inline a:hover { border-color: var(--accent); color: var(--accent); }

/* === Content === */
.content p { margin: 1.2rem 0; }
.content ul, .content ol { margin: 1rem 0; padding-left: 1.5rem; }
.content li { margin: 0.3rem 0; }
.content blockquote {
  border-left: 3px solid var(--accent); padding: 0.5rem 1rem;
  color: var(--muted); margin: 1.5rem 0; background: var(--surface);
}
.content pre {
  background: var(--code-bg); padding: 1rem 1.25rem;
  border-radius: 6px; overflow-x: auto; margin: 1.5rem 0;
  font-family: var(--mono); font-size: 0.85rem; line-height: 1.5;
  border: 1px solid var(--border);
}
.content code { font-family: var(--mono); font-size: 0.88em; }
.content p code, .content li code {
  background: var(--code-bg); padding: 0.15rem 0.4rem;
  border-radius: 3px; font-size: 0.85em;
}
.content img { max-width: 100%; height: auto; border-radius: 6px; margin: 1.5rem 0; }
.content table {
  width: 100%; border-collapse: collapse; margin: 1.5rem 0;
  font-size: 0.9rem;
}
.content th, .content td { padding: 0.6rem 0.8rem; border: 1px solid var(--border); text-align: left; }
.content th { background: var(--surface); font-weight: 600; }
.content hr { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }

/* === Article list === */
.article-list article {
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--border);
}
.article-list article:last-child { border-bottom: none; }
.article-list h2, .article-list h3 { margin: 0 0 0.25rem; }
.article-list h2 a, .article-list h3 a { color: var(--fg); }
.article-list h2 a:hover, .article-list h3 a:hover { color: var(--accent); }
.article-list p { margin: 0.5rem 0 0; color: var(--muted); font-size: 0.92rem; }
.article-count { color: var(--muted); font-size: 0.9rem; }

/* === Breadcrumb === */
.breadcrumb { margin: 2rem 0 0; font-size: 0.8rem; color: var(--muted); }
.breadcrumb ol { list-style: none; display: flex; gap: 0.3rem; padding: 0; }
.breadcrumb li::after { content: "›"; margin-left: 0.3rem; }
.breadcrumb li:last-child::after { content: ""; }
.breadcrumb a { color: var(--muted); }

/* === TOC === */
.toc {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 6px; padding: 0; margin: 1.5rem 0;
  float: right; max-width: 280px; margin-left: 1.5rem;
}
.toc summary { padding: 0.75rem 1rem; cursor: pointer; font-weight: 600; font-size: 0.9rem; }
.toc nav, .toc ul { padding: 0 1rem 0.75rem; }
.toc ul { list-style: none; }
.toc li { margin: 0.2rem 0; font-size: 0.85rem; }
.toc a { color: var(--muted); }
.toc a:hover { color: var(--accent); }

/* === Related === */
.related {
  margin-top: 3rem; padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}
.related h2 { font-size: 1.1rem; margin-bottom: 0.75rem; }
.related ul { list-style: none; padding: 0; }
.related li { margin: 0.75rem 0; }
.related a { font-weight: 500; }
.related-desc { display: block; font-size: 0.85rem; color: var(--muted); margin-top: 0.15rem; }

/* === Homepage === */
.hero { padding: 2rem 0 1rem; }
.hero h1 { font-size: 2.2rem; }
.hero p { font-size: 1.05rem; color: var(--muted); max-width: 600px; }
.featured h2, .topics h2 { font-size: 1.2rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; }
.view-all { margin-top: 1rem; }
.view-all a { font-weight: 600; }

/* === Topic grid === */
.topic-grid { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 0.75rem; }
.topic-link {
  background: var(--surface); border: 1px solid var(--border);
  padding: 0.4rem 0.8rem; border-radius: 4px; font-size: 0.85rem;
  color: var(--fg); text-decoration: none;
}
.topic-link:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.topic-link .count { color: var(--muted); font-size: 0.8em; }

/* === Footer === */
footer[role="contentinfo"] {
  margin-top: 3rem; padding: 1.5rem 0;
  border-top: 1px solid var(--border);
  font-size: 0.8rem; color: var(--muted);
}
footer nav { display: flex; gap: 1.5rem; margin-bottom: 0.5rem; }
footer a { color: var(--muted); }
footer a:hover { color: var(--accent); }

/* === Pagination === */
.pagination { display: flex; justify-content: center; gap: 0.5rem; margin: 2rem 0; }
.pagination a, .pagination span {
  padding: 0.4rem 0.8rem; border: 1px solid var(--border); border-radius: 3px;
  font-size: 0.85rem; color: var(--muted);
}
.pagination .active { background: var(--accent); color: #fff; border-color: var(--accent); }

/* === Responsive === */
@media (max-width: 640px) {
  html { font-size: 16px; }
  h1 { font-size: 1.6rem; }
  .toc { float: none; max-width: 100%; margin-left: 0; }
}

/* === Print === */
@media print {
  header[role="banner"], footer, .toc, .related, .breadcrumb, .tags { display: none; }
  body { max-width: 100%; font-size: 12pt; }
  a { color: inherit; text-decoration: underline; }
}