:root{
  --bg:#f5f7fb; --ink:#172033; --muted:#647084; --accent:#2563eb; --accent2:#0f766e;
  --card:#fff; --line:#dfe5ee; --chip:#eef6ff; --shadow:0 18px 42px rgba(31,41,55,.08);
}
*{box-sizing:border-box}
html{max-width:100%;overflow-x:hidden}
body{margin:0;background:linear-gradient(180deg,#fff 0,#f5f7fb 34rem);color:var(--ink);line-height:1.7;
  font-family:-apple-system,BlinkMacSystemFont,"Apple SD Gothic Neo","Malgun Gothic",sans-serif}
a{color:inherit;text-decoration:none}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px 84px}
.sf{position:absolute;left:-9999px;opacity:0;width:0;height:0}

/* home */
header.site{padding:40px 0 14px}
header.site h1{font-size:34px;font-weight:850;margin:0 0 6px}
header.site .tag{margin:0;color:var(--muted)}
.banner{display:block;background:var(--chip);border:1px solid #dbeafe;border-radius:12px;
  padding:12px 16px;margin:8px 0 20px;font-size:14px;color:#1d4ed8;font-weight:700}
.banner .when{color:#8a94a6;font-weight:600}
.filters{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:0 0 22px}
.filters .fcap{color:var(--muted);font-size:12px;font-weight:800;margin-right:2px}
.filters label{border:1px solid var(--line);background:#fff;color:#475569;border-radius:999px;
  padding:7px 13px;font-size:13px;font-weight:750;cursor:pointer;transition:.15s}
.filters label:hover{border-color:#9cc3ff;color:var(--accent)}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:16px}
.card{display:flex;flex-direction:column;gap:8px;background:var(--card);border:1px solid var(--line);
  border-radius:14px;padding:18px 18px 16px;transition:.18s;min-height:150px}
.card:hover{transform:translateY(-3px);box-shadow:var(--shadow);border-color:#b8cdf4}
.card .emoji{font-size:26px}
.card h3{font-size:17px;margin:0;font-weight:800}
.card .sum{font-size:13.5px;color:#4b5563;margin:0;flex:1}
.card .meta{font-size:12px;color:var(--muted);font-weight:700}

/* reader (B) */
.home{display:inline-block;margin:18px 0 12px;font-size:13px;font-weight:750;color:var(--accent)}
.book{display:grid;grid-template-columns:260px minmax(0,1fr);gap:26px;align-items:start}
.toc{position:sticky;top:16px;border:1px solid var(--line);background:#fff;border-radius:12px;padding:14px 14px;font-size:13.5px}
.toc-h{font-weight:800;margin-bottom:8px}
.toc ul{margin:0;padding-left:0;list-style:none;display:flex;flex-direction:column;gap:6px}
.toc a{color:#475569}
.toc a.cur{color:var(--accent);font-weight:800}
.toc .dft{color:#9aa3b2;font-size:11px;border:1px solid var(--line);border-radius:6px;padding:0 5px}
.reader{min-width:0}
.reader .label{font-size:12px;font-weight:800;letter-spacing:.06em;color:var(--accent2);text-transform:uppercase}
.reader h1{font-size:30px;font-weight:850;margin:6px 0 18px}
.reader h2{font-size:22px;margin:30px 0 10px}
.reader h3{font-size:18px;margin:22px 0 8px}
.reader p{margin:12px 0}
.reader ul,.reader ol{margin:12px 0;padding-left:22px}
.reader blockquote{margin:14px 0;padding:6px 14px;border-left:3px solid var(--accent);background:#f8fafc;color:#475569}
.reader code{background:#eef2f7;padding:1px 6px;border-radius:6px;font-family:"SF Mono",ui-monospace,Menlo,monospace;font-size:.92em}
.reader pre{background:#0f172a;color:#e2e8f0;padding:14px 16px;border-radius:10px;overflow:auto;margin:14px 0}
.reader pre code{background:none;padding:0;color:inherit}
.reader table{border-collapse:collapse;margin:14px 0;width:100%}
.reader th,.reader td{border:1px solid var(--line);padding:7px 10px;text-align:left;font-size:14px}
.reader th{background:#f1f5f9}
.reader hr{border:none;border-top:1px solid var(--line);margin:24px 0}
/* diagrams / figures (svg + html-fig passthrough) */
.reader .diagram{margin:22px 0;padding:18px 16px;border:1px solid var(--line);border-radius:12px;
  background:#fbfcfe;overflow-x:auto;text-align:center;container-type:inline-size}
.reader .diagram svg{max-width:100%;height:auto}
.reader .diagram figcaption{margin-top:12px;font-size:12.5px;color:var(--muted);font-weight:700}
/* lightweight box-and-arrow kit so HTML figures look consistent without SVG.
   Default = vertical stack (never breaks); horizontal only when the figure is
   wide enough (container query) — so it reflows naturally as the window resizes. */
.diagram .flow{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px}
.diagram .col{display:flex;flex-direction:column;gap:10px;align-items:center}
.diagram .node{display:inline-flex;align-items:center;justify-content:center;text-align:center;
  padding:10px 14px;border:1.5px solid var(--accent);border-radius:10px;background:#fff;
  font-size:13px;font-weight:750;color:var(--ink);min-width:84px}
.diagram .node.alt{border-color:var(--accent2);background:#f0fdfa}
.diagram .node.dim{border-color:var(--line);color:var(--muted);font-weight:600;background:#fff}
.diagram .arrow{display:inline-block;color:var(--muted);font-weight:800;font-size:18px;line-height:1;
  transform:rotate(90deg)}
.diagram .group{border:1.5px dashed var(--line);border-radius:12px;padding:12px;
  display:flex;flex-direction:column;gap:10px;align-items:center}
.diagram .group .lbl{font-size:11px;font-weight:800;color:var(--muted);letter-spacing:.04em}
/* wide enough → lay the flow out horizontally with right-pointing arrows */
@container (min-width:520px){
  .diagram .flow{flex-direction:row;flex-wrap:nowrap}
  .diagram .arrow{transform:none}
}
.pager{display:flex;align-items:center;justify-content:space-between;margin:34px 0 6px;font-size:14px;font-weight:750}
.pager .nav{color:var(--accent)}
.pager .nav.off{color:#c2c8d2}
.pager .pos{color:var(--muted);font-weight:800}
.bar{height:6px;background:#e8edf4;border-radius:999px;overflow:hidden}
.bar i{display:block;height:100%;background:linear-gradient(90deg,var(--accent),var(--accent2))}
@media(max-width:760px){.book{grid-template-columns:1fr}.toc{position:static}}