:root{
    --bg:#fbfaf8; --panel:#fff; --ink:#1b1a18; --muted:#5d5850; --rule:#e3ded5;
    --accent:#0f6f63; --accent-soft:#e6f1ef; --warn:#8a5a00; --warn-soft:#fdf3e0;
    --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,monospace;
    --serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,serif;
  }
  @media (prefers-color-scheme:dark){
    :root{ --bg:#14150f; --panel:#1c1e17; --ink:#eceadf; --muted:#a29b8c; --rule:#33362b;
           --accent:#5fd3bf; --accent-soft:#12302c; --warn:#e0b356; --warn-soft:#2e2413; }
  }
  *{box-sizing:border-box}
  body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--serif);
       font-size:17px;line-height:1.65;-webkit-font-smoothing:antialiased}
  .wrap{max-width:60rem;margin:0 auto;padding:3rem 1.25rem 5rem}
  header{border-bottom:2px solid var(--ink);padding-bottom:1.25rem;margin-bottom:1.5rem}
  .eyebrow{font-family:var(--mono);font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;
           color:var(--accent);margin:0 0 .5rem}
  h1{font-size:2.1rem;line-height:1.15;margin:0 0 .5rem;letter-spacing:-.01em}
  .sub{color:var(--muted);margin:0;font-size:1.02rem}
  h2{font-size:1.4rem;margin:3rem 0 .75rem;letter-spacing:-.01em;
     border-bottom:1px solid var(--rule);padding-bottom:.35rem}
  h2 .num{font-family:var(--mono);font-size:.8rem;color:var(--accent);margin-right:.55rem;
          vertical-align:.15em}
  h3{font-size:1.05rem;margin:1.9rem 0 .4rem;font-family:var(--mono);font-weight:600;
     color:var(--accent)}
  p{margin:.7rem 0}
  code{font-family:var(--mono);font-size:.85em;background:var(--accent-soft);
       padding:.1em .35em;border-radius:3px;color:var(--ink)}
  .lead{font-size:1.12rem}
  .toc{background:var(--panel);border:1px solid var(--rule);border-radius:10px;
       padding:1rem 1.25rem;margin:1.5rem 0 0}
  .toc ol{margin:.35rem 0;padding-left:1.3rem}
  .toc li{margin:.2rem 0}
  .toc a{text-decoration:none}
  .toc a:hover{text-decoration:underline}

  /* Diagram cards stay light in BOTH themes on purpose. Mermaid bakes its text and
     stroke colours into the SVG at render time; they cannot follow prefers-color-scheme.
     A dark card would render the diagram invisible - the same dark-on-dark failure that
     makes the VS Code markdown preview go black. */
  figure{margin:1.5rem 0 .5rem;background:#fff;border:1px solid var(--rule);
         border-radius:10px;padding:1.25rem;overflow-x:auto}
  .diagram{display:block;width:100%;height:auto;max-width:100%}
  figcaption{font-family:var(--mono);font-size:.75rem;color:#5d5850;margin-top:.9rem;
             text-align:center;line-height:1.5}

  table{width:100%;border-collapse:collapse;margin:1rem 0;font-size:.92rem}
  th,td{text-align:left;padding:.6rem .7rem;border-bottom:1px solid var(--rule);vertical-align:top}
  th{font-family:var(--mono);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;
     color:var(--muted);border-bottom:1.5px solid var(--rule)}
  td:first-child{font-family:var(--mono);font-size:.82rem}
  tbody tr:hover{background:var(--accent-soft)}
  .scroll{overflow-x:auto}

  .note{background:var(--panel);border-left:3px solid var(--accent);padding:.85rem 1rem;
        margin:1.25rem 0;border-radius:0 6px 6px 0;font-size:.95rem}
  .note.warn{border-left-color:var(--warn);background:var(--warn-soft)}
  .note p{margin:.35rem 0}
  .keystone{border:2px solid var(--accent);background:var(--accent-soft);border-radius:10px;
            padding:1.1rem 1.25rem;margin:1.5rem 0}
  .keystone p{margin:.4rem 0}
  .keystone .k{font-family:var(--mono);font-size:.7rem;letter-spacing:.12em;
               text-transform:uppercase;color:var(--accent);display:block;margin-bottom:.35rem}
  footer{margin-top:3.5rem;padding-top:1rem;border-top:1px solid var(--rule);
         font-family:var(--mono);font-size:.75rem;color:var(--muted)}
  a{color:var(--accent)}

/* --- added for the modular pages: navigation, hub grid, inline mermaid --- */
.crumb{font-family:var(--mono);font-size:.75rem;letter-spacing:.04em;margin:0 0 1.5rem}
.crumb a{text-decoration:none}
.crumb a:hover{text-decoration:underline}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(15rem,1fr));gap:1rem;margin:1.5rem 0}
.card{display:block;background:var(--panel);border:1px solid var(--rule);border-radius:10px;
      padding:1rem 1.15rem;text-decoration:none;color:var(--ink)}
a.card:hover{border-color:var(--accent)}
.card h3{margin:.1rem 0 .3rem;font-size:1.05rem}
.card p{margin:.2rem 0;font-size:.92rem;color:var(--muted)}
/* feature-grid cards are plain <div>s, not links - h3 there is a feature name, not a page title,
   so it drops the mono/accent styling h3 carries in running prose */
div.card h3{font-family:inherit;color:var(--ink);font-weight:600}
.pill{display:inline-block;font-family:var(--mono);font-size:.65rem;font-weight:600;
  letter-spacing:.06em;text-transform:uppercase;color:var(--accent);background:var(--accent-soft);
  border-radius:9999px;padding:.1em .55em;margin-left:.4em;vertical-align:.12em}
/* mermaid replaces the <pre> source with an <svg>; keep it centered inside the light card */
.mermaid{display:flex;justify-content:center;margin:0}
.mermaid svg{max-width:100%;height:auto}

/* shared diagram-legend skeleton (size/shape only) - each page defines its own swatch colors
   locally, since the same swatch class can mean a different thing on a different page's diagram */
.legend{display:flex;flex-wrap:wrap;gap:.6rem 1.6rem;align-items:center;
  font-family:var(--mono);font-size:.78rem;color:var(--muted);margin:1.25rem 0 0}
.legend .swatch{display:inline-block;width:.85rem;height:.85rem;border-radius:3px;
  margin-right:.4rem;vertical-align:-1px;border:1.5px solid}
.legend .line{display:inline-block;width:1.7rem;height:0;margin-right:.4rem;
  vertical-align:3px;border-top:2px solid var(--ink)}
.legend .line.dotted{border-top-style:dotted;border-top-width:2.5px}

/* end-of-page forward link, so a reader can move through every page without going back to the hub */
.next-page{display:flex;justify-content:space-between;align-items:center;gap:1rem;
  background:var(--accent-soft);border:1px solid var(--rule);border-radius:10px;
  padding:1rem 1.25rem;margin:2.5rem 0 0;text-decoration:none;color:var(--ink)}
.next-page:hover{border-color:var(--accent)}
.next-page .k{display:block;font-family:var(--mono);font-size:.7rem;letter-spacing:.12em;
  text-transform:uppercase;color:var(--accent);margin-bottom:.2rem}
.next-page .title{font-size:1.05rem;font-weight:600}
.next-page .arrow{font-size:1.4rem;color:var(--accent);flex:none}

.imprint{margin:.6rem 0 0}
.imprint a{color:inherit}
.imprint a:hover{text-decoration:underline}