/* qdnu.ai site system v1 — SITE_SYSTEM.md §3–§6. Single light theme. */

*, *::before, *::after { box-sizing: border-box; margin: 0; }

:root {
  /* ground and ink */
  --bg:        #FCFCFB;   /* page */
  --bg-2:      #F3F4F1;   /* panels, asides, code blocks */
  --ink:       #1C2229;   /* body text, headings */
  --ink-2:     #4A535C;   /* ledes, secondary text */
  --muted:     #6E7780;   /* captions, meta, eyebrow labels — never body text */
  --rule:      #DFE1DC;   /* hairlines */

  /* the two accents, semantic and fixed */
  --sys:       #0E93AB;   /* signal / system / links / current-nav */
  --sys-soft:  #D9EEF2;
  --anc:       #B8720F;   /* register / ancilla / "next" / warnings */
  --anc-soft:  #F6E9D3;

  /* surface ramp for the E/I page's Plotly colorscale — tints of --sys, not a third hue */
  --surf-lo:   #E3F1F4;
  --surf-hi:   #0A5E6E;

  /* type */
  --f-serif:   "Newsreader", Georgia, "Times New Roman", serif;
  --f-sans:    "Source Sans 3", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-mono:    "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  /* measure and rhythm */
  --measure:   68ch;
  --col:       720px;
  --col-wide:  920px;
  --gutter:    20px;
  --space:     1rem;
}

html { color-scheme: light; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--f-sans);
  font-size: 17.5px;
  line-height: 1.55;
}

/* ── Column ──────────────────────────────────────────────────────── */
main.col { max-width: var(--col); margin: 0 auto; padding: 0 var(--gutter) 96px; }
main.col.wide { max-width: var(--col-wide); }

/* ── Type ────────────────────────────────────────────────────────── */
h1, h2, h3 { font-family: var(--f-serif); font-weight: 500; letter-spacing: -0.01em; text-wrap: balance; }
h1 { font-size: clamp(2.1rem, 5vw, 3rem); line-height: 1.1; font-optical-sizing: auto; }
h2 { font-size: 1.55rem; line-height: 1.2; margin-top: 2.6rem; margin-bottom: .6rem; }
h3 { font-size: 1.2rem; margin-top: 1.6rem; margin-bottom: .3rem; }
p { margin: .7rem 0; max-width: var(--measure); }
.lede { font-family: var(--f-serif); font-size: 1.3rem; line-height: 1.4; color: var(--ink-2); max-width: 34em; margin-top: 1.1rem; }
.eyebrow { font-size: .76rem; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); }
.caption, .meta { font-size: .9rem; color: var(--muted); }
a { color: var(--sys); text-decoration: none; }
a:hover { text-decoration: underline; }
code, .mono { font-family: var(--f-mono); font-size: .95rem; font-variant-numeric: tabular-nums; }
code { background: var(--bg-2); padding: 1px 5px; border-radius: 3px; font-size: .9em; }
ul, ol { padding-left: 1.2rem; max-width: var(--measure); }
li { margin: .3rem 0; }

/* inline and display math — hand-set HTML, no scripts */
.m { font-family: var(--f-serif); font-style: italic; font-size: 1.06em; }
.m .up, .eq .up { font-style: normal; }
.eq { font-family: var(--f-serif); font-size: 1.3rem; text-align: center; margin: 1rem 0; line-height: 1.5; }
.eq i { font-style: italic; }
.eq sub, .eq sup, .m sub, .m sup { font-size: .68em; font-style: normal; }

/* ── Nav ─────────────────────────────────────────────────────────── */
nav.site {
  max-width: var(--col-wide); margin: 0 auto; padding: 18px var(--gutter);
  display: flex; align-items: baseline; justify-content: space-between;
  flex-wrap: wrap; gap: 8px 24px;
  border-bottom: 1px solid var(--rule);
}
nav.site .logo { font-family: var(--f-serif); font-size: 1.25rem; font-weight: 500; color: var(--ink); }
nav.site .logo small { font-family: var(--f-sans); font-size: .8rem; font-weight: 400; color: var(--muted); margin-left: 8px; }
nav.site .links { display: flex; flex-wrap: wrap; gap: 4px 20px; }
nav.site .links a { color: var(--ink-2); font-size: .95rem; padding-bottom: 2px; }
nav.site .links a:hover { color: var(--sys); text-decoration: none; }
nav.site .links a.on { color: var(--sys); border-bottom: 2px solid var(--sys); }

/* ── Page header ─────────────────────────────────────────────────── */
header.page { padding-top: 52px; }
header.page h1 { margin-top: .6rem; }

/* ── .moves — the numbered arc list (Home) ───────────────────────── */
.moves { list-style: none; padding: 0; margin: 1.2rem 0; max-width: none; counter-reset: move; }
.moves > li {
  display: grid; grid-template-columns: 48px minmax(0, 1fr); gap: 0 8px;
  padding: 1.1rem 0; border-bottom: 1px solid var(--rule);
  counter-increment: move;
}
.moves > li::before {
  content: counter(move); font-family: var(--f-serif); font-size: 1.6rem;
  color: var(--muted); line-height: 1.2;
}
.moves b { font-weight: 600; }
.moves .meta { display: block; margin-top: .3rem; }

/* ── .entries — the Notebook / Papers index list ─────────────────── */
.entries { list-style: none; padding: 0; margin: 1.2rem 0; max-width: none; }
.entries > li {
  display: grid; grid-template-columns: 48px minmax(0, 1fr) minmax(0, 17rem); gap: 0 12px;
  align-items: baseline;
  padding: 1rem 0; border-bottom: 1px solid var(--rule);
}
.entries .num { font-family: var(--f-mono); font-size: .95rem; color: var(--muted); }
.entries .meta { font-family: var(--f-mono); font-size: .85rem; color: var(--muted); text-align: right; font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.entries a { color: var(--ink); font-weight: 600; }
.entries a:hover { color: var(--sys); }
.entries .sum { display: block; color: var(--ink-2); font-size: .95rem; margin-top: .15rem; }
.entries > li.next { color: var(--muted); }
.entries > li.next .num { color: var(--anc); }
.entries > li.next b { font-weight: 600; }
@media (max-width: 520px) {
  .entries > li { grid-template-columns: 48px minmax(0, 1fr); }
  .entries .meta { grid-column: 2; text-align: left; margin-top: .2rem; }
}

/* ── .mat — matrix / number block ────────────────────────────────── */
.mat {
  background: var(--bg-2); border: 1px solid var(--rule); border-radius: 4px;
  padding: 12px 16px; margin: .8rem 0;
  font-family: var(--f-mono); font-size: .95rem; line-height: 1.5;
  font-variant-numeric: tabular-nums;
  white-space: pre; overflow-x: auto; max-width: 100%;
}
.mat .lab { font-family: var(--f-sans); font-size: .76rem; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); }
.mat .sys { color: var(--sys); }
.mat .anc { color: var(--anc); }

/* ── .stat — a labelled number ───────────────────────────────────── */
.stat { padding: 12px 16px; border-left: 3px solid var(--rule); margin: .8rem 0; }
.stat.sys { border-color: var(--sys); }
.stat.anc { border-color: var(--anc); }
.stat b { display: block; font-size: .76rem; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); }
.stat .v { font-family: var(--f-mono); font-size: 1.4rem; line-height: 1.25; font-variant-numeric: tabular-nums; }
.stat small { display: block; color: var(--muted); font-size: .9rem; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 12px; margin: 1rem 0; }
.stats .stat { margin: 0; }

/* ── .panel — controls or asides ─────────────────────────────────── */
.panel { background: var(--bg-2); border-radius: 6px; padding: 16px 20px; margin: 1.4rem 0; }
.panel p { max-width: none; }

/* ── Figures ─────────────────────────────────────────────────────── */
figure { margin: 1.4rem calc((var(--col) - var(--col-wide)) / 2); max-width: var(--col-wide); }
main.col figure { margin-left: 0; margin-right: 0; max-width: 100%; }
figure svg, figure img, figure canvas { max-width: 100%; height: auto; display: block; }
figcaption { font-size: .9rem; color: var(--muted); margin-top: .5rem; max-width: 70ch; line-height: 1.45; }

/* ── .status — inline pill ───────────────────────────────────────── */
.status {
  display: inline-block; font-size: .76rem; font-weight: 600;
  letter-spacing: .08em; text-transform: uppercase;
  color: var(--muted); background: var(--bg-2);
  padding: 2px 9px; border-radius: 999px; vertical-align: middle;
}
.status.next { color: var(--anc); background: var(--anc-soft); }

/* ── .banner — archive strip ─────────────────────────────────────── */
.banner {
  background: var(--anc-soft); color: #4a3208;
  font-family: var(--f-sans); font-size: .9rem;
  padding: 10px var(--gutter); text-align: center;
}
.banner a { color: #4a3208; text-decoration: underline; }

/* ── Tables ──────────────────────────────────────────────────────── */
.table-wrap { overflow-x: auto; max-width: 100%; margin: .8rem 0; }
table { border-collapse: collapse; width: 100%; font-size: .95rem; }
th, td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--rule); vertical-align: top; }
th { font-size: .74rem; letter-spacing: .1em; text-transform: uppercase; color: var(--muted); font-weight: 600; }
td.num, th.num { font-family: var(--f-mono); font-variant-numeric: tabular-nums; text-align: right; }

/* ── Footer ──────────────────────────────────────────────────────── */
footer#foot .inner {
  max-width: var(--col-wide); margin: 48px auto 0; padding: 20px var(--gutter) 40px;
  border-top: 1px solid var(--rule);
  font-size: .9rem; color: var(--muted);
}
footer#foot a { color: var(--sys); }

/* ── Global overflow guards ──────────────────────────────────────── */
img, svg, canvas, video, iframe { max-width: 100%; }

/* ================================================================
   Page-specific blocks (spec §5: no page carries a <style> block)
   ================================================================ */

/* Notebook 01 — one qubit from two electrodes */
body.nb-one-qubit .wide { max-width: var(--col-wide); margin-inline: auto; }
body.nb-one-qubit .flow { overflow-x: auto; }
body.nb-one-qubit header.page { border-bottom: 1px solid var(--rule); padding-bottom: 22px; }
body.nb-one-qubit header.page .meta { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px 24px; margin-top: 28px; padding-top: 18px; border-top: 1px solid var(--rule); color: var(--ink); font-size: .92rem; font-family: var(--f-sans); text-align: left; }
body.nb-one-qubit header.page .meta div { font-size: .92rem; }
body.nb-one-qubit header.page .meta b { display: block; font-size: .72rem; letter-spacing: .12em; text-transform: uppercase; color: var(--muted); font-weight: 600; margin-bottom: 2px; }
body.nb-one-qubit .tag { display: inline-block; font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; font-weight: 600; padding: 2px 8px; border-radius: 3px; vertical-align: middle; }
body.nb-one-qubit .tag.sys { background: var(--sys-soft); color: var(--sys); }
body.nb-one-qubit .tag.anc { background: var(--anc-soft); color: var(--anc); }
body.nb-one-qubit .step { display: grid; grid-template-columns: 56px minmax(0, 1fr); gap: 16px; margin-top: 3rem; align-items: start; }
body.nb-one-qubit .step .n { font-family: var(--f-serif); font-size: 2.4rem; line-height: 1; color: var(--muted); font-weight: 400; padding-top: .15rem; }
body.nb-one-qubit .step h2 { margin-top: 0; }
body.nb-one-qubit .row { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px; align-items: start; }
body.nb-one-qubit .note { background: var(--bg-2); border-radius: 6px; padding: 16px 20px; margin: 1.4rem 0; max-width: none; }
body.nb-one-qubit .note p { max-width: none; }
body.nb-one-qubit .honest { border-top: 1px solid var(--rule); margin-top: 3.5rem; padding-top: 1.5rem; }
body.nb-one-qubit main footer { margin-top: 4rem; font-size: .85rem; color: var(--muted); border-top: 1px solid var(--rule); padding-top: 1rem; }
@media (max-width: 520px) { body.nb-one-qubit .step { grid-template-columns: minmax(0, 1fr); } body.nb-one-qubit .step .n { font-size: 1.6rem; } }

/* Notebook 02 — the E/I unit on a pattern pair */
body.nb-ei-unit .mat { display: inline-grid; grid-template-columns: auto auto; gap: 2px 18px; padding: 6px 14px; background: none; border: 0; border-left: 1.5px solid currentColor; border-right: 1.5px solid currentColor; border-radius: 6px; font-family: var(--f-mono); font-size: 1rem; vertical-align: middle; font-style: normal; white-space: normal; overflow: visible; margin: 0; }
body.nb-ei-unit .controls { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px 28px; align-items: end; }
body.nb-ei-unit .ctl label { display: block; font-size: .74rem; letter-spacing: .12em; text-transform: uppercase; color: var(--muted); font-weight: 600; }
body.nb-ei-unit .ctl .val { font-family: var(--f-mono); font-size: 1.1rem; margin: 2px 0 4px; }
body.nb-ei-unit .ctl input[type=range] { width: 100%; accent-color: var(--sys); }
body.nb-ei-unit .ctl.anc input[type=range] { accent-color: var(--anc); }
body.nb-ei-unit .presets { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
body.nb-ei-unit .presets button { font: inherit; font-size: .9rem; padding: 5px 12px; border: 1px solid var(--rule); background: var(--bg); color: var(--ink); border-radius: 4px; cursor: pointer; }
body.nb-ei-unit .presets button:hover { border-color: var(--sys); }
body.nb-ei-unit .presets button:focus-visible { outline: 2px solid var(--sys); outline-offset: 2px; }
body.nb-ei-unit .plot { width: 100%; height: 360px; }
body.nb-ei-unit .plot3 { width: 100%; height: 460px; }
body.nb-ei-unit .grid2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(380px, 1fr)); gap: 20px; }
body.nb-ei-unit .regime { display: inline-block; padding: 2px 10px; border-radius: 3px; font-size: .78rem; letter-spacing: .1em; text-transform: uppercase; font-weight: 600; }
body.nb-ei-unit .regime.osc { background: var(--sys-soft); color: var(--sys); }
body.nb-ei-unit .regime.sep { background: var(--anc-soft); color: var(--anc); }
body.nb-ei-unit .regime.ep { background: var(--bg-2); color: var(--ink-2); }
body.nb-ei-unit .row { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 20px; align-items: start; }
body.nb-ei-unit .note { border-top: 1px solid var(--rule); margin-top: 3rem; padding-top: 1.4rem; }
body.nb-ei-unit header.page { border-bottom: 1px solid var(--rule); padding-bottom: 22px; }
body.nb-ei-unit main footer { margin-top: 3rem; font-size: .85rem; color: var(--muted); border-top: 1px solid var(--rule); padding-top: 1rem; }
@media (max-width: 520px) { body.nb-ei-unit .grid2 { grid-template-columns: minmax(0, 1fr); } body.nb-ei-unit .plot3 { height: 380px; } }