:root {
  /* Both palettes are defined below, so the browser should not invert the
     page when the reader asks for dark. The blue, the grey-blue and the
     yellow are the logo's: nodes, edges and the selected node. */
  color-scheme: light dark;
  --bg: #f3f5f8;
  --card: #ffffff;
  --line: #dce2ea;
  --ink: #1b2430;
  --muted: #5d6877;
  --accent: #176aac;
  --accent-fill: #dcebf7;
  --edge: #a9b7cc;
  --pick: #f2b705;
  --pick-fill: #fdf1c4;
  --good: #2f7d4f;
  --warn: #9a5b00;
  --bad: #b3261e;
  --bad-fill: #fbe9e7;
  --code: #f6f8fa;
  /* One colour per component in the whole-formula drawing; the mix with the
     card colour gives the fill, so the same eight serve both palettes. */
  --comp-1: #176aac;
  --comp-2: #d9822b;
  --comp-3: #3f9c5a;
  --comp-4: #9b59b6;
  --comp-5: #d1495b;
  --comp-6: #2a9d8f;
  --comp-7: #8a8f1f;
  --comp-8: #7a5c3e;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14181d;
    --card: #1b2027;
    --line: #2d343d;
    --ink: #e4e8ec;
    --muted: #9aa3ad;
    --accent: #6cb0e8;
    --accent-fill: #1c3347;
    --edge: #56657a;
    --pick: #f5c211;
    --pick-fill: #4a3d0e;
    --good: #6fc28f;
    --warn: #e0a24a;
    --bad: #f28b82;
    --bad-fill: #3d1f1d;
    --code: #151a20;
    --comp-1: #6cb0e8;
    --comp-2: #eea060;
    --comp-3: #6fc28f;
    --comp-4: #c38fd8;
    --comp-5: #ef7d8c;
    --comp-6: #5cc2b5;
    --comp-7: #c4c957;
    --comp-8: #c49a74;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.55 var(--sans);
}

main {
  margin: 0 auto;
  padding: 1.5rem 2rem 4rem;
}

@media (max-width: 40rem) {
  main { padding: 1rem 1rem 3rem; }
}

header { margin-bottom: 1.5rem; max-width: 60rem; }

h1 {
  margin: 0 0 0.35rem;
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

h1 a { color: var(--accent); text-decoration: none; }

h2 {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
}

h3 {
  margin: 0 0 0.4rem;
  font-size: 13px;
  font-weight: 600;
}

.lede { margin: 0; color: var(--muted); }

a { color: var(--accent); }

code, kbd {
  font: 0.9em/1 var(--mono);
  background: var(--code);
  border-radius: 3px;
  padding: 0.1em 0.3em;
}

kbd { border: 1px solid var(--line); }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 1.1rem;
  margin-bottom: 1.25rem;
}

/* Input beside the controls once there is room for both. */
.io { display: grid; gap: 1.1rem; }

@media (min-width: 56rem) {
  .io { grid-template-columns: minmax(0, 1fr) 15rem; }
}

label, legend, figcaption {
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--muted);
}

label { display: block; margin-bottom: 0.3rem; }

.examples {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.7rem;
  margin-bottom: 1rem;
}

.lead { font-size: 14px; font-weight: 500; }
#examples { display: flex; flex-wrap: wrap; gap: 0.4rem; }

#examples button {
  width: auto;
  padding: 0.3rem 0.75rem;
  border-color: transparent;
  border-radius: 999px;
  background: var(--accent-fill);
  color: var(--accent);
  font-size: 13px;
}

#examples button:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--card);
  color: var(--accent);
}

#examples button.chosen, #examples button.chosen:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--card);
}

textarea, select, input {
  width: 100%;
  color: var(--ink);
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 0.4rem 0.55rem;
  font: 14px/1.4 var(--sans);
}

input[type="checkbox"] { width: auto; margin: 0 0.35rem 0 0; }

/* The box grows to the height of the settings beside it. */
.cnf-input { display: flex; flex-direction: column; min-height: 22rem; }

textarea {
  flex: 1;
  min-height: 12rem;
  resize: vertical;
  font: 13px/1.45 var(--mono);
  background: var(--code);
}

textarea:disabled { color: var(--muted); }

textarea:focus, select:focus, input:focus, button:focus-visible, summary:focus-visible,
.text-view:focus-visible, .tree-view:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.input-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.3rem 0.5rem;
  margin-bottom: 0.3rem;
}

.input-head label { margin-bottom: 0; }

/* A file held over the page will become the input. */
body.dropping textarea {
  outline: 2px dashed var(--accent);
  outline-offset: 1px;
}

.controls { display: grid; gap: 0.7rem; align-content: start; margin: 0; }
.field { margin: 0; }

.stages {
  margin: 0;
  padding: 0.35rem 0.6rem 0.5rem;
  border: 1px solid var(--line);
  border-radius: 5px;
}

.stages legend { padding: 0 0.25rem; }

label.check {
  display: flex;
  align-items: center;
  margin: 0.2rem 0 0;
  font-size: 14px;
  letter-spacing: 0;
  text-transform: none;
  color: var(--ink);
}

label.check:has(input:disabled) { color: var(--muted); }

button {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid var(--accent);
  border-radius: 5px;
  background: var(--accent);
  color: var(--card);
  font: 500 15px/1.4 var(--sans);
  cursor: pointer;
}

button:hover:not(:disabled) { background: var(--card); color: var(--accent); }

/* Cancel takes Prepare's place while a run is on, and the pointer says the
   page is busy everywhere but on it. */
#cancel { background: var(--card); color: var(--accent); }
#cancel:hover { background: var(--accent); color: var(--card); }
body.busy, body.busy :not(#cancel) { cursor: progress; }
button:disabled { opacity: 0.45; cursor: default; }

#status, .note {
  margin: 0;
  font-size: 13px;
  color: var(--muted);
}

#status { overflow-wrap: anywhere; }

.result-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.3rem 0.8rem;
  margin-bottom: 0.8rem;
}

.result-head button, #open, .exports button, .zoom button {
  width: auto;
  padding: 0.1rem 0.55rem;
  font-size: 12px;
}

#stale { color: var(--warn); }

/* ------------------------------------------------------------- summary */

.stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 2rem;
  margin: 0 0 0.9rem;
}

.stat {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--muted);
}

.stat b {
  font-size: 1.6rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0;
  text-transform: none;
  color: var(--accent);
}

.stat .from {
  font-size: 1rem;
  font-weight: 500;
  color: var(--muted);
}

.status-line {
  margin: 0 0 0.8rem;
  padding: 0.55rem 0.75rem;
  border-left: 4px solid var(--good);
  background: var(--code);
  border-radius: 0 5px 5px 0;
  max-width: 60rem;
}

.status-line.fully_resolved { border-left-color: var(--accent); }
.status-line.refuted { border-left-color: var(--warn); }

.status-line.failed {
  border-left-color: var(--bad);
  background: var(--bad-fill);
}

.status-line strong { font-weight: 600; }

.status-line pre {
  margin: 0.4rem 0 0;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font: 13px/1.45 var(--mono);
}

.facts {
  display: grid;
  grid-template-columns: max-content minmax(0, 1fr);
  gap: 0.25rem 1rem;
  margin: 0 0 1rem;
  font-size: 14px;
}

.facts dt { color: var(--muted); }
.facts dd { margin: 0; overflow-wrap: anywhere; }

.lift {
  font: 15px/1.4 var(--mono);
  color: var(--ink);
}

.exports {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
  margin: 0 0 1rem;
}

.exports .lead { margin-right: 0.3rem; }

/* -------------------------------------------------------------- panels */

.panels { display: grid; gap: 1.1rem; }

@media (min-width: 72rem) {
  .panels { grid-template-columns: minmax(0, 2fr) minmax(0, 3fr); }
}

.panel { margin: 0; min-width: 0; }

figcaption {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.3rem 0.5rem;
  margin-bottom: 0.4rem;
}

.caption-label { margin: 0; }

figcaption select {
  width: auto;
  max-width: 100%;
  padding: 0.15rem 0.35rem;
  font-size: 13px;
  text-transform: none;
  letter-spacing: 0;
}

.meta {
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
}

.zoom {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
  letter-spacing: 0;
  text-transform: none;
}

.zoom b {
  display: inline-block;
  min-width: 3.2em;
  text-align: center;
  font-weight: 500;
  font-variant-numeric: tabular-nums;
}

/* The file on show: only the lines in view are on the page, so a formula
   of any size scrolls at the same speed. */
.text-view {
  position: relative;
  height: 36rem;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--code);
  font: 12.5px/20px var(--mono);
}

.text-spacer { width: 1px; }

.text-lines {
  position: absolute;
  top: 0;
  left: 0;
  min-width: 100%;
  padding: 0 0.6rem 0 0;
}

.text-lines div { height: 20px; white-space: pre; }

.text-lines span {
  display: inline-block;
  min-width: 4.5em;
  padding: 0 0.8em 0 0.5em;
  margin-right: 0.6em;
  text-align: right;
  color: var(--muted);
  border-right: 1px solid var(--line);
  user-select: none;
}

.text-lines div.cut { color: var(--muted); font-style: italic; }

.tree-box { display: grid; gap: 0.7rem; }

.tree-view {
  position: relative;
  height: 36rem;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--code);
  cursor: grab;
  touch-action: none;
}

.tree-view.dragging { cursor: grabbing; }

.tree-view canvas { display: block; width: 100%; height: 100%; }

.tree-empty {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  text-align: center;
  background: var(--code);
  cursor: default;
}

.details {
  padding: 0.6rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 6px;
}

.details dl {
  display: grid;
  grid-template-columns: max-content minmax(0, 1fr);
  gap: 0.15rem 0.9rem;
  margin: 0;
  font-size: 13.5px;
}

.details dt { color: var(--muted); }
.details dd { margin: 0; overflow-wrap: anywhere; }
.details .chain { font-family: var(--mono); font-size: 13px; }

.swatch {
  display: inline-block;
  width: 0.8em;
  height: 0.8em;
  margin-right: 0.35em;
  vertical-align: -0.05em;
  border-radius: 2px;
}

.hint {
  margin: 0.5rem 0 0;
  font-size: 13px;
  color: var(--muted);
}

details { margin-top: 0.6rem; }

summary {
  cursor: pointer;
  font-size: 13px;
  color: var(--muted);
}

#outline {
  max-height: 24rem;
  overflow: auto;
  margin-top: 0.4rem;
  font: 13px/1.5 var(--mono);
}

#outline ul { margin: 0; padding-left: 1.2rem; list-style: none; }
#outline > ul { padding-left: 0; }