:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --line: #e2e8f0;
  --brand: #0369a1;
  --brand-dark: #075985;
  --soft: #f0f9ff;
  --radius: 10px;
  --measure: 46rem;
  color-scheme: light;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  word-break: keep-all;
  overflow-wrap: break-word;
}
a { color: var(--brand); text-underline-offset: 3px; }
a:hover { color: var(--brand-dark); }
:focus-visible { outline: 3px solid var(--brand); outline-offset: 2px; border-radius: 4px; }

.wrap { max-width: var(--measure); margin: 0 auto; padding: 0 20px; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--surface); padding: 8px 12px; z-index: 10; }
.skip:focus { left: 8px; }

.site-header { background: var(--surface); border-bottom: 1px solid var(--line); }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; min-height: 60px; gap: 12px; }
.brand { font-weight: 800; font-size: 1.1rem; color: var(--text); text-decoration: none; letter-spacing: -0.01em; }
.brand span { color: var(--brand); font-weight: 700; }
.site-header nav { display: flex; gap: 4px; }
.site-header nav a { display: inline-flex; align-items: center; min-height: 44px; padding: 0 10px; color: var(--muted); text-decoration: none; font-size: 0.95rem; }
.site-header nav a:hover { color: var(--brand); }

.intro { padding-top: 40px; padding-bottom: 8px; }
.intro h1 { font-size: 1.6rem; line-height: 1.4; margin: 0 0 12px; letter-spacing: -0.02em; }
.intro p { color: var(--muted); margin: 0; }

.cards { list-style: none; padding: 0; margin: 28px 0 56px; display: grid; gap: 14px; }
.card a { display: block; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px 22px; color: inherit; text-decoration: none; transition: border-color .2s ease, box-shadow .2s ease; }
.card a:hover { border-color: var(--brand); box-shadow: 0 2px 10px rgba(3, 105, 161, .08); }
.card h2 { font-size: 1.15rem; line-height: 1.45; margin: 0 0 8px; letter-spacing: -0.01em; }
.card p { margin: 0 0 10px; color: var(--muted); font-size: 0.95rem; line-height: 1.65; }
.card .more { color: var(--brand); font-weight: 600; font-size: 0.95rem; }

.post { padding-top: 28px; padding-bottom: 48px; }
.crumb { margin: 0 0 8px; font-size: 0.9rem; }
.crumb a { color: var(--muted); }
.post h1 { font-size: 1.65rem; line-height: 1.4; margin: 0 0 10px; letter-spacing: -0.02em; }
.meta { color: var(--muted); font-size: 0.92rem; margin: 0 0 24px; }

.toc { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 20px; margin: 0 0 28px; }
.toc-title { font-weight: 700; margin: 0 0 4px; font-size: 0.95rem; }
.toc ol { margin: 0; padding-left: 1.3em; }
.toc li { font-size: 0.95rem; line-height: 1.6; padding: 3px 0; }
.toc a { color: var(--text); text-decoration: none; }
.toc a:hover { color: var(--brand); text-decoration: underline; }

.prose h2 { font-size: 1.3rem; line-height: 1.45; margin: 44px 0 12px; padding-top: 12px; border-top: 1px solid var(--line); letter-spacing: -0.01em; scroll-margin-top: 16px; }
.prose h3 { font-size: 1.1rem; margin: 28px 0 8px; }
.prose p { margin: 0 0 16px; }
.prose .basis { font-size: 0.88rem; line-height: 1.65; color: var(--muted); background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px 14px; }
.prose ul, .prose ol { padding-left: 1.3em; margin: 0 0 16px; }
.prose li { margin: 4px 0; }
.prose blockquote { margin: 0 0 16px; padding: 12px 16px; background: var(--soft); border: 1px solid var(--line); border-radius: var(--radius); }
.prose blockquote p:last-child { margin: 0; }
.prose strong { font-weight: 700; }
.prose code { font-size: 0.9em; background: var(--soft); padding: 1px 5px; border-radius: 4px; }

.table-wrap { overflow-x: auto; margin: 0 0 20px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); -webkit-overflow-scrolling: touch; }
.table-wrap table { border-collapse: collapse; width: 100%; min-width: 520px; font-size: 0.93rem; line-height: 1.6; }
.table-wrap th, .table-wrap td { padding: 10px 12px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.table-wrap th { background: var(--soft); font-weight: 700; white-space: nowrap; }
.table-wrap tr:last-child td { border-bottom: 0; }
.table-wrap td { font-variant-numeric: tabular-nums; }

.tags { list-style: none; padding: 0; margin: 32px 0 0; display: flex; flex-wrap: wrap; gap: 8px; }
.tags li { font-size: 0.85rem; color: var(--muted); background: var(--surface); border: 1px solid var(--line); border-radius: 999px; padding: 2px 12px; }
.back { margin: 24px 0 0; }

.site-footer { border-top: 1px solid var(--line); background: var(--surface); padding: 24px 0 32px; color: var(--muted); font-size: 0.9rem; }
.site-footer p { margin: 0 0 4px; }
.site-footer .links { display: flex; flex-wrap: wrap; gap: 4px 16px; margin-top: 8px; }
.site-footer .links a { color: var(--muted); display: inline-flex; min-height: 32px; align-items: center; }

@media (min-width: 768px) {
  body { font-size: 18px; }
  .intro h1 { font-size: 2rem; }
  .post h1 { font-size: 2rem; }
  .prose h2 { font-size: 1.4rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}

@media print {
  .site-header nav, .toc, .site-footer .links, .back { display: none; }
  .table-wrap { overflow: visible; border: 0; }
}