/* Layout: drafting sheet. Concept index rail on the left, one concept sheet on the right, depth dial above both. */
:root {
  --paper: #E9EEF3;
  --sheet: #FAFBFC;
  --ink: #142030;
  --muted: #566377;
  --line: #CDD6E0;
  --grid: rgba(31, 95, 209, .07);
  --accent: #1F5FD1;
  --l1: #23876A;
  --l2: #1F5FD1;
  --l3: #B4532A;
  --display: "Bricolage Grotesque", "Segoe UI", system-ui, sans-serif;
  --body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0E141C; --sheet: #141C27; --ink: #E3E9F1; --muted: #93A0B3; --line: #283444;
    --grid: rgba(118, 162, 242, .06); --accent: #76A2F2; --l1: #5CC4A2; --l2: #76A2F2; --l3: #EC8D5E;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0E141C; --sheet: #141C27; --ink: #E3E9F1; --muted: #93A0B3; --line: #283444;
  --grid: rgba(118, 162, 242, .06); --accent: #76A2F2; --l1: #5CC4A2; --l2: #76A2F2; --l3: #EC8D5E;
  color-scheme: dark;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background-color: var(--paper);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--ink);
  font: 16px/1.6 var(--body);
}
.app { max-width: 1180px; margin: 0 auto; padding-inline: clamp(16px, 4vw, 40px); padding-block: 36px 48px; display: grid; gap: 28px; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* Header */
.top { display: flex; flex-wrap: wrap; gap: 24px; align-items: end; justify-content: space-between; }
.brand { min-width: 0; flex: 1 1 380px; }
.eyebrow { font: 500 12px/1 var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--accent); margin: 0 0 12px; }
h1 { font: 700 clamp(36px, 5.5vw, 58px)/1 var(--display); letter-spacing: -.025em; margin: 0; text-wrap: balance; }
.lede { color: var(--muted); max-width: 56ch; margin: 14px 0 0; }

/* Depth dial */
[data-depth="0"], [data-d="0"] { --c: var(--l1); }
[data-depth="1"], [data-d="1"] { --c: var(--l2); }
[data-depth="2"], [data-d="2"] { --c: var(--l3); }
.dial { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); border: 1px solid var(--line); border-radius: 10px; background: var(--sheet); overflow: hidden; width: min(100%, 540px); }
.dial button { all: unset; cursor: pointer; display: grid; gap: 4px; align-content: start; padding: 12px 14px 14px; border-left: 1px solid var(--line); }
.dial button:first-child { border-left: 0; }
.dial button:hover { background: color-mix(in srgb, var(--c) 6%, var(--sheet)); }
.dial button[aria-checked="true"] { background: color-mix(in srgb, var(--c) 13%, var(--sheet)); box-shadow: inset 0 -3px 0 var(--c); }
.dial button:focus-visible, .lv:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
.dial b, .lv b { font: 500 12px var(--mono); color: var(--c); }
.dial .nm { font-weight: 600; font-size: 15px; }
.dial small { color: var(--muted); font-size: 12.5px; line-height: 1.35; }
.bars { display: flex; gap: 3px; align-items: end; height: 14px; }
.bars i { width: 5px; background: var(--line); border-radius: 1px; }
.bars i:nth-child(1) { height: 6px; }
.bars i:nth-child(2) { height: 10px; }
.bars i:nth-child(3) { height: 14px; }
.bars[data-lv="0"] i:nth-child(1), .bars[data-lv="1"] i:nth-child(-n+2), .bars[data-lv="2"] i { background: var(--c); }

/* Index rail */
.layout { display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: 28px; align-items: start; }
.index { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 16px); display: grid; gap: 18px; max-height: calc(100vh - 32px); overflow: auto; min-width: 0; }
#q { width: 100%; font: inherit; font-size: 14px; padding: 9px 12px; border: 1px solid var(--line); border-radius: 8px; background: var(--sheet); color: var(--ink); }
#q:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
#nav { display: grid; gap: 18px; }
.group h3 { font: 500 11px/1 var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--muted); margin: 0 0 6px 10px; }
.group ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 1px; }
.group a { display: flex; justify-content: space-between; gap: 8px; padding: 6px 10px; border-radius: 6px; color: var(--ink); text-decoration: none; font-size: 14.5px; }
.group a:hover { background: var(--sheet); }
.group a:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
.group a[aria-current="page"] { background: var(--ink); color: var(--paper); }
.group .n { font: 12px var(--mono); color: var(--muted); font-variant-numeric: tabular-nums; }
.group a[aria-current="page"] .n { color: inherit; opacity: .7; }
.empty { color: var(--muted); font-size: 14px; margin: 0 10px; }

/* Concept sheet */
.sheet { background: var(--sheet); border: 1px solid var(--line); border-radius: 12px; padding: clamp(20px, 4vw, 44px); min-width: 0; outline: none; }
.meta { display: flex; justify-content: space-between; gap: 12px; font: 500 12px var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.sheet h2 { font: 700 clamp(30px, 4.5vw, 46px)/1.05 var(--display); letter-spacing: -.02em; margin: 14px 0 10px; text-wrap: balance; }
.tag { font-size: 18px; color: var(--muted); margin: 0 0 28px; max-width: 60ch; }

.ladder { display: grid; margin-bottom: 8px; }
.rung { display: grid; grid-template-columns: 160px minmax(0, 1fr); gap: 20px; padding: 16px 0; border-top: 1px solid var(--line); cursor: pointer; }
.rung.on { cursor: default; }
.lv { all: unset; cursor: pointer; display: grid; gap: 4px; align-content: start; }
.lv span:last-child { font-weight: 600; font-size: 14.5px; }
.rung:not(.on) .lv span:last-child { color: var(--muted); font-weight: 500; }
.rung p { margin: 0; max-width: 66ch; }
.rung:not(.on) p { color: var(--muted); font-size: 15px; display: -webkit-box; -webkit-line-clamp: 1; -webkit-box-orient: vertical; overflow: hidden; }
.rung:not(.on):hover p { color: var(--ink); }
.rung.on p { font-size: 17.5px; line-height: 1.7; }

.facts { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 28px; border-top: 1px solid var(--line); padding-top: 24px; }
.facts > div { min-width: 0; }
h4 { font: 500 12px var(--mono); letter-spacing: .12em; text-transform: uppercase; color: var(--muted); margin: 0 0 10px; }
.trade { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.trade li { padding-left: 24px; position: relative; }
.trade li::before { content: "\2194"; position: absolute; left: 0; color: var(--accent); font-family: var(--mono); }
.trade.key li::before { content: "\25B8"; }
h4.sp { margin-top: 20px; }

/* Architecture blueprint */
.note { font: 12.5px/1.5 var(--mono); color: var(--muted); margin: -16px 0 24px; }
.blueprint { display: grid; gap: 10px; margin-bottom: 28px; }
.blueprint h4 { margin: 8px 0 0; }
.scale { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px 20px; margin: 0; }
.scale div { border-top: 1px solid var(--ink); padding-top: 8px; min-width: 0; }
.scale dt { font: 12px/1.4 var(--mono); color: var(--muted); }
.scale dd { margin: 4px 0 0; font: 600 19px/1.25 var(--display); font-variant-numeric: tabular-nums; }
.flow { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; align-items: center; gap: 8px 6px; }
.flow li { display: flex; align-items: center; gap: 6px; font: 13px var(--mono); }
.flow li + li::before { content: "\2192"; color: var(--accent); }
.flow span { padding: 6px 10px; border: 1px solid var(--line); border-radius: 6px; background: var(--paper); }

.ask { border: 1px dashed var(--line); border-radius: 8px; padding: 14px 16px; background: var(--paper); }
.ask p { margin: 0; font-size: 15.5px; }
.nums-wrap { overflow-x: auto; margin-top: 24px; }
.nums { width: 100%; border-collapse: collapse; font-size: 14px; font-variant-numeric: tabular-nums; }
.nums td { padding: 6px 0; border-bottom: 1px solid var(--line); }
.nums td:last-child { text-align: right; font-family: var(--mono); padding-left: 16px; white-space: nowrap; }
.related { display: flex; flex-wrap: wrap; gap: 8px; }
.related a { font: 13px var(--mono); padding: 4px 10px; border: 1px solid var(--line); border-radius: 999px; color: var(--ink); text-decoration: none; }
.related a:hover, .related a:focus-visible { border-color: var(--accent); color: var(--accent); outline: none; }
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 32px; padding-top: 20px; border-top: 1px solid var(--line); }
.pager a { color: var(--accent); text-decoration: none; font-weight: 500; }
.pager a:last-child { text-align: right; margin-left: auto; }
.pager a span { display: block; font: 12px var(--mono); color: var(--muted); }

footer { font: 12px var(--mono); color: var(--muted); }
kbd { font: 12px var(--mono); border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 4px; padding: 1px 5px; background: var(--sheet); }

@media (prefers-reduced-motion: no-preference) {
  .rung.on p { animation: rise .22s ease-out; }
  @keyframes rise { from { transform: translateY(4px); } to { transform: none; } }
}
@media (max-width: 820px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .index { position: static; max-height: none; overflow: visible; }
  #nav { display: flex; gap: 16px; overflow-x: auto; padding-bottom: 6px; }
  .group { flex: none; }
  .group ul { display: flex; gap: 4px; }
  .group a { white-space: nowrap; }
}
@media (max-width: 560px) {
  .rung { grid-template-columns: minmax(0, 1fr); gap: 6px; }
  .dial small { display: none; }
}