/* Layout: instrument bench — controls rail | parameter plane | analysis bench.
   The plane is a dark "photographic plate" in both themes; panels follow the theme. */
:root {
  --bg: #f3f5f8;
  --surface: #ffffff;
  --surface-2: #eef1f6;
  --ink: #1a2130;
  --muted: #5d6679;
  --line: #d8dde7;
  --accent: #2c4bd1;
  --accent-ink: #ffffff;
  --accent-soft: #e3e8fb;
  --warn: #a35a00;
  --bad: #b3261e;
  --good: #1d7a4a;
  --plate: #0b0e14;
  --plate-ink: #dfe5f0;
  --focus: #2c4bd1;

  --f-math: "STIX Two Text", "Cambria Math", "Times New Roman", serif;
  --f-ui: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;

  --s-xs: 0.75rem;
  --s-sm: 0.8125rem;
  --s-md: 0.9375rem;
  --s-lg: 1.25rem;
  --s-xl: 1.6rem;
  --r: 6px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0e1117;
    --surface: #151a23;
    --surface-2: #1b212c;
    --ink: #e4e8ef;
    --muted: #98a1b3;
    --line: #2a3242;
    --accent: #8fa3ff;
    --accent-ink: #0e1117;
    --accent-soft: #232c45;
    --warn: #f0b35a;
    --bad: #ff8a80;
    --good: #6fd19b;
    --plate: #07090d;
    --plate-ink: #dfe5f0;
    --focus: #8fa3ff;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0e1117;
  --surface: #151a23;
  --surface-2: #1b212c;
  --ink: #e4e8ef;
  --muted: #98a1b3;
  --line: #2a3242;
  --accent: #8fa3ff;
  --accent-ink: #0e1117;
  --accent-soft: #232c45;
  --warn: #f0b35a;
  --bad: #ff8a80;
  --good: #6fd19b;
  --plate: #07090d;
  --plate-ink: #dfe5f0;
  --focus: #8fa3ff;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 400 var(--s-md) / 1.45 var(--f-ui);
  -webkit-font-smoothing: antialiased;
}
button, input, select { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }

/* ---------------------------------------------------------------- header */
.top {
  display: flex;
  align-items: baseline;
  gap: 1.25rem;
  flex-wrap: wrap;
  padding: 0.7rem 16px 0.6rem;
  border-bottom: 1px solid var(--line);
  background: var(--surface);
}
.brand {
  font: italic 600 var(--s-xl) / 1 var(--f-math);
  letter-spacing: 0.01em;
  margin: 0;
}
.byline {
  font: 400 var(--s-sm) / 1 var(--f-ui);
  font-style: normal;
  letter-spacing: 0;
  color: var(--muted);
  text-decoration: none;
  margin-left: 0.35rem;
  white-space: nowrap;
}
.byline:hover, .byline:focus-visible { color: var(--accent); text-decoration: underline; }
.eq {
  font: 400 1.15rem / 1.2 var(--f-math);
  color: var(--ink);
  white-space: nowrap;
}
.eq i { font-style: italic; }
.eq .dim { color: var(--muted); }
.top .status {
  margin-left: auto;
  font: 400 var(--s-xs) / 1.3 var(--f-mono);
  color: var(--muted);
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
.status b { color: var(--ink); font-weight: 500; }
.theme-btn {
  border: 1px solid var(--line);
  background: var(--surface-2);
  border-radius: var(--r);
  padding: 0.2rem 0.55rem;
  font-size: var(--s-xs);
  cursor: pointer;
}

/* ---------------------------------------------------------------- layout */
.bench {
  display: grid;
  grid-template-columns: 300px minmax(380px, 1.05fr) minmax(380px, 1fr);
  gap: 0;
  height: calc(100% - 3.4rem);
  min-height: 600px;
}
.rail {
  border-right: 1px solid var(--line);
  background: var(--surface);
  overflow-y: auto;
  padding: 0.9rem 16px 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
  min-width: 0;
  overflow-x: hidden; /* never scroll sideways (Safari sizes long field content otherwise) */
}
.rail > * { min-width: 0; max-width: 100%; }
.platecol {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding: 0.9rem 16px;
  min-width: 0;
  overflow-y: auto;
}
/* the plate keeps its size when an explanation opens below it: the column scrolls instead */
.platecol > * { flex-shrink: 0; }
.analysis {
  border-left: 1px solid var(--line);
  background: var(--surface);
  padding: 0.9rem 16px 2rem;
  overflow-y: auto;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}
/* never squeeze a block to fit: the column scrolls instead (a shrunk block was overdrawn by the plot) */
.analysis > * { flex-shrink: 0; }
@media (max-width: 1240px) {
  .bench { grid-template-columns: 300px 1fr; height: auto; }
  .analysis { grid-column: 1 / -1; border-left: 0; border-top: 1px solid var(--line); }
}
@media (max-width: 760px) {
  .bench { grid-template-columns: 1fr; }
  .rail { border-right: 0; border-bottom: 1px solid var(--line); }
  .eq { white-space: normal; }
}

/* ---------------------------------------------------------------- controls */
.group { display: flex; flex-direction: column; gap: 0.55rem; }
.group > h2 {
  margin: 0;
  font: 600 var(--s-xs) / 1 var(--f-ui);
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--muted);
}
.field { display: flex; flex-direction: column; gap: 0.2rem; min-width: 0; }
.field > label, .lbl {
  font-size: var(--s-sm);
  color: var(--muted);
}
.field > label i, .lbl i { font-family: var(--f-math); font-size: 1.05em; color: var(--ink); }
.row { display: flex; gap: 0.5rem; align-items: end; }
.row > * { flex: 1; min-width: 0; }
input[type="text"], input[type="number"], select, textarea {
  width: 100%;
  border: 1px solid var(--line);
  background: var(--bg);
  border-radius: var(--r);
  padding: 0.38rem 0.5rem;
  font-family: var(--f-mono);
  font-size: var(--s-sm);
  min-width: 0;
}
select { font-family: var(--f-ui); }
input.err, textarea.err { border-color: var(--bad); }
textarea#expr {
  display: block;
  resize: vertical;
  height: calc(3 * 1.45em + 0.9rem); /* three lines, then it scrolls */
  min-height: calc(2 * 1.45em + 0.9rem);
  line-height: 1.45;
  overflow-x: hidden;
  overflow-y: auto;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  word-break: break-all;
  color: var(--ink);
}
.hint { font-size: var(--s-xs); color: var(--muted); margin: 0; overflow-wrap: anywhere; }
.fnref { font-size: var(--s-xs); }
.fnref > summary { cursor: pointer; color: var(--accent); width: max-content; max-width: 100%; }
.fnref-list {
  margin-top: 0.35rem;
  max-height: 18rem;
  overflow-y: auto;
  overflow-x: hidden;
  border: 1px solid var(--line);
  border-radius: var(--r);
  padding: 0.25rem 0.5rem 0.5rem;
  background: var(--bg);
}
.fnref-list h3 {
  margin: 0.55rem 0 0.2rem;
  font: 600 var(--s-xs) / 1.3 var(--f-ui);
  color: var(--muted);
}
.fnref-list .fn { display: block; padding: 0.15rem 0; overflow-wrap: anywhere; }
.fnref-list .fn button {
  font: var(--s-xs) / 1.3 var(--f-mono);
  color: var(--accent);
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
  text-align: left;
  overflow-wrap: anywhere;
}
.fnref-list .fn button:hover { text-decoration: underline; }
.fnref-list .fn span { display: block; color: var(--muted); }
.hint:empty { display: none; }
.tag {
  font: 600 0.65rem / 1 var(--f-ui);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  border: 1px solid currentColor;
  border-radius: 3px;
  padding: 0.05rem 0.25rem;
  margin-left: 0.25rem;
  vertical-align: 1px;
}
.hint.err { color: var(--bad); }
.mono { font-family: var(--f-mono); font-size: var(--s-xs); font-variant-numeric: tabular-nums; }
.seg {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: var(--r);
  overflow: hidden;
  width: 100%;
}
.seg button {
  flex: 1;
  border: 0;
  background: var(--bg);
  padding: 0.35rem 0.4rem;
  font-size: var(--s-sm);
  cursor: pointer;
  border-right: 1px solid var(--line);
}
.seg button:last-child { border-right: 0; }
.seg button[aria-pressed="true"] { background: var(--accent); color: var(--accent-ink); }
.btn {
  border: 1px solid var(--line);
  background: var(--surface-2);
  border-radius: var(--r);
  padding: 0.45rem 0.7rem;
  font-size: var(--s-sm);
  font-weight: 500;
  cursor: pointer;
}
.btn:hover { border-color: var(--muted); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn:disabled { opacity: 0.5; cursor: default; }
.btns { display: flex; gap: 0.5rem; flex-wrap: wrap; }
details > summary {
  cursor: pointer;
  font-size: var(--s-sm);
  color: var(--muted);
  list-style: none;
}
details > summary::before { content: "▸ "; }
details[open] > summary::before { content: "▾ "; }
details > .group { margin-top: 0.6rem; }
.cf {
  background: var(--surface-2);
  border-radius: var(--r);
  padding: 0.45rem 0.55rem;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

/* ---------------------------------------------------------------- plate */
.plate-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  max-height: calc(100vh - 11rem);
  max-width: 100%;
  margin-inline: auto;
  background: var(--plate);
  border-radius: var(--r);
  overflow: hidden;
  touch-action: none;
}
.plate-wrap canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
#plane { image-rendering: auto; }
#overlay { cursor: crosshair; }
.plate-axes {
  position: absolute;
  left: 0.5rem;
  bottom: 0.4rem;
  font: 400 var(--s-xs) / 1.3 var(--f-mono);
  color: var(--plate-ink);
  background: rgb(7 9 13 / 0.6);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  pointer-events: none;
}
.plate-progress {
  position: absolute;
  left: 0; top: 0;
  height: 2px;
  background: #8fa3ff;
  transition: width 0.15s linear;
  pointer-events: none;
}
.readout {
  /* exactly one line: hovering must never change the plate's size */
  display: flex;
  gap: 1rem;
  flex-wrap: nowrap;
  overflow: hidden;
  white-space: nowrap;
  font: 400 var(--s-xs) / 1.4 var(--f-mono);
  color: var(--muted);
  height: 1.4em;
  font-variant-numeric: tabular-nums;
}
.readout span { flex: 0 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; }
.readout b { color: var(--ink); font-weight: 500; }
.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.9rem;
  font-size: var(--s-xs);
  color: var(--muted);
}
.legend span { display: inline-flex; align-items: center; gap: 0.35rem; font-variant-numeric: tabular-nums; }
.legend i {
  width: 0.8rem; height: 0.8rem; border-radius: 2px; display: inline-block;
  box-shadow: inset 0 0 0 1px rgb(127 127 127 / 0.35);
}
.legend b { color: var(--ink); font-weight: 500; }
.plate-tools { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }
.plate-tools .hint { margin-left: auto; }

/* ---------------------------------------------------------------- analysis */
.verdict {
  /* one line: verdict, λ, structure, parameter */
  display: flex;
  align-items: baseline;
  gap: 0.8rem;
  flex-wrap: nowrap;
  white-space: nowrap;
  min-width: 0;
}
.verdict h2 { margin: 0; font: 600 var(--s-lg) / 1.2 var(--f-ui); flex: 0 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; }
.verdict h2 .dot { display: inline-block; width: 0.7em; height: 0.7em; border-radius: 50%; margin-right: 0.4em; vertical-align: 0.05em; }
.verdict .vline { font-size: var(--s-sm); color: var(--ink); flex: 0 0 auto; }
.verdict .vline .k { color: var(--muted); }
.verdict .param { font: 400 var(--s-sm) / 1 var(--f-mono); color: var(--muted); margin-left: auto; flex: 0 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis; }
.section-ctl { margin: 0; }
.summary { border-top: 1px solid var(--line); padding-top: 0.6rem; }
.summary > summary { cursor: pointer; font-size: var(--s-sm); color: var(--ink); font-weight: 500; }
.summary[open] > summary { margin-bottom: 0.6rem; }
.summary .note { margin-bottom: 0.6rem; }
.chip {
  display: inline-flex; align-items: center; gap: 0.35rem;
  font-size: var(--s-xs);
  font-weight: 600;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--line);
}
.chip i { width: 0.55rem; height: 0.55rem; border-radius: 50%; display: inline-block; }
.metrics {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(8.5rem, 1fr));
  border: 1px solid var(--line);
  border-radius: var(--r);
  overflow: hidden;
  background: var(--surface);
}
.metric {
  padding: 0.45rem 0.6rem;
  min-width: 0;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  margin: 0 -1px -1px 0;
}
.metric .k { font-size: var(--s-xs); color: var(--muted); }
.metric .k i { font-family: var(--f-math); font-size: 1.1em; color: var(--ink); }
.metric .v {
  font: 500 var(--s-md) / 1.3 var(--f-mono);
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}
.metric .v.good { color: var(--good); }
.metric .v.warn { color: var(--warn); }
.metric .v.bad { color: var(--bad); }
.tabs { display: flex; gap: 0; border-bottom: 1px solid var(--line); flex-wrap: wrap; }
.tabs button {
  border: 0;
  background: none;
  padding: 0.45rem 0.75rem;
  font-size: var(--s-sm);
  color: var(--muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
}
.tabs button[aria-selected="true"] { color: var(--ink); border-bottom-color: var(--accent); font-weight: 500; }
.plot { width: 100%; height: 360px; min-width: 0; }
.plot.tall { height: 420px; }
.panel[hidden] { display: none !important; }
.note { font-size: var(--s-sm); color: var(--muted); margin: 0; max-width: 65ch; }
.note i { font-family: var(--f-math); }
.cands { width: 100%; border-collapse: collapse; font: 400 var(--s-xs) / 1.4 var(--f-mono); }
.cands th, .cands td { text-align: right; padding: 0.15rem 0.4rem; border-bottom: 1px solid var(--line); }
.cands th { color: var(--muted); font-weight: 500; }
.cands tr.on td { color: var(--accent); font-weight: 600; }
.table-wrap { overflow-x: auto; }
.cands-wrap { max-height: 22rem; overflow-y: auto; border: 1px solid var(--line); border-radius: var(--r); }
.cands-wrap .cands { border-collapse: separate; border-spacing: 0; }
.cands-wrap .cands th { position: sticky; top: 0; background: var(--surface); z-index: 1; box-shadow: 0 1px 0 var(--line); }
.cands-wrap .cands tr:first-child th { padding-top: 0.35rem; }
.struct-row { align-items: end; margin-bottom: 0.5rem; }
.struct-row > .field { flex: 0 0 auto; }
.struct-row select { width: auto; }
.struct-row .note { margin: 0 0 0.3rem; }
.empty {
  border: 1px dashed var(--line);
  border-radius: var(--r);
  padding: 1rem;
  color: var(--muted);
  font-size: var(--s-sm);
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}

/* ---- slice panel and the "Move along" walker */
.slice-row { flex-wrap: wrap; }
.slice-row > .field { flex: 0 1 auto; }
.slice-row .seg button { padding: 0.38rem 0.6rem; }
.slice-pick { min-width: 12rem; }
.pick-row { display: flex; gap: 0.3rem; }
.pick-row select { flex: 1; min-width: 0; max-width: 26rem; text-overflow: ellipsis; }
.pick-row .btn { flex: 0 0 2.2rem; padding: 0.3rem 0; }
.comp-seg { margin-top: 0.4rem; }
.comp-seg button { padding: 0.3rem 0.7rem; }
#draw-hint { margin: 0.3rem 0 0; min-height: 1.4em; }
.slice-sliders { display: grid; grid-template-columns: 3fr 2fr auto; gap: 0.5rem 1rem; align-items: end; margin: 0.6rem 0 0; }
.range-row { display: flex; gap: 0.5rem; align-items: center; min-width: 0; }
.slice-sliders > .field { min-width: 0; }
.slice-sliders .range-row input[type="range"] { flex: 1 1 auto; width: auto; min-width: 3rem; }
.slice-sliders input[type="range"], .walk input[type="range"] { width: 100%; accent-color: var(--accent); }
.slice-cap select { width: 4.6rem; }
.slice-cap label { white-space: nowrap; }
#slice-count { margin: 0.3rem 0 0; min-height: 1.4em; }
@media (max-width: 640px) { .slice-sliders { grid-template-columns: 1fr; } }
.slice-help { margin-top: 0.4rem; }
.slice-help summary { cursor: pointer; color: var(--ink); }
.slice-help p { margin: 0.4rem 0 0; }
.walk {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
  margin-top: 0.4rem;
  font-size: var(--s-sm);
  color: var(--muted);
}
.walk select { width: auto; flex: 0 0 auto; }
.walk input[type="range"] { flex: 1; min-width: 8rem; width: auto; }
/* three-state motion control: ◀ backwards, ❚❚ pause, ▶ forwards (fixed widths: no jitter) */
.seg.play-seg { flex: 0 0 auto; width: auto; display: inline-flex; }
.seg.play-seg button { flex: 0 0 2rem; width: 2rem; padding: 0.25rem 0; text-align: center; font-size: 0.8rem; line-height: 1.2; }

/* ---- compact left panel: inline labels for short names */
.hint:empty { display: none; }
.group.tight { gap: 0.4rem; }
.il { display: flex; align-items: center; gap: 0.4rem; min-width: 0; }
.il > label, .il > .lbl { flex: 0 0 auto; min-width: 1.6rem; font-size: var(--s-sm); color: var(--muted); }
.il > label i { font-family: var(--f-math); font-size: 1.08em; color: var(--ink); }
.il > input, .il > select { flex: 1 1 0; min-width: 0; width: auto; }
.il > .plus { flex: 0 0 auto; color: var(--muted); font-size: var(--s-sm); }
.il > .plus i { font-family: var(--f-math); color: var(--ink); }
.il > .btn { flex: 0 0 auto; }
.il > .seg { flex: 1 1 auto; width: auto; }
.il-pair { display: flex; gap: 0.8rem; }
.il-pair > .il { flex: 1 1 0; }
.il-head > label { font: 400 1.05rem / 1.2 var(--f-math); color: var(--ink); }
.il-head > label i { font-size: 1em; }
.il-T > select { flex: 0 0 7.2rem; }
.il-axes > select { flex: 1 1 0; }
label.on-plane, label.on-plane i { color: var(--accent) !important; font-weight: 600; }
.cf-wrap > summary { font-size: var(--s-xs); color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.cf-wrap[open] > summary { margin-bottom: 0.35rem; }
details.adv { gap: 0.55rem; }
details.adv > summary { font: 600 var(--s-xs) / 1 var(--f-ui); text-transform: uppercase; letter-spacing: 0.09em; color: var(--muted); }
details.adv:not([open]) { gap: 0; }
.rail .il > label, .rail .il > .lbl { min-width: 2.6rem; }
.il-pair .il > label { min-width: 1.6rem; }
.slice-pick > select { max-width: 30rem; }
.slice-pick > .btn { flex: 0 0 2.2rem; padding: 0.3rem 0; }

/* ---- left panel: name | field | separator or name | field, so every field lines up */
.pg { display: grid; grid-template-columns: 2.4rem minmax(0, 1fr) 1.9rem minmax(0, 1fr); gap: 0.4rem; align-items: center; }
.pg > label, .pg > .sep { font-size: var(--s-sm); color: var(--muted); white-space: nowrap; }
.pg > label i, .pg > .sep i { font-family: var(--f-math); font-size: 1.08em; color: var(--ink); }
.pg > .sep, .pg > label[data-sep] { text-align: center; }
.pg > input, .pg > select { width: 100%; min-width: 0; }
.pg-wide > select { grid-column: 2 / -1; }
details.sec > .sec-body { margin-top: 0.55rem; }
details.sec > summary { font: 600 var(--s-xs) / 1 var(--f-ui); text-transform: uppercase; letter-spacing: 0.09em; color: var(--muted); }
.draw-seg button { padding: 0.35rem 0.2rem; }

/* ---- expandable explanations under the plots, and the drawing help */
.note:empty { display: none; }
details.whatis { font-size: var(--s-sm); color: var(--muted); max-width: 70ch; }
details.whatis > summary { cursor: pointer; color: var(--accent); font-size: var(--s-sm); width: max-content; max-width: 100%; }
details.whatis p, details.whatis ul { margin: 0.45rem 0 0; line-height: 1.45; }
details.whatis ul { padding-left: 1.1rem; }
details.whatis b { color: var(--ink); font-weight: 600; }
.platecol details.whatis { margin-top: 0.2rem; }
ul.draw-help { margin: 0.35rem 0 0; padding-left: 1rem; color: var(--muted); line-height: 1.4; }
ul.draw-help li { margin-bottom: 0.25rem; }
ul.draw-help li.on { color: var(--ink); }
ul.draw-help li.on::marker { color: var(--accent); }