:root {
  color-scheme: light;
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --muted: #898781;
  --grid: #e1e0d9;
  --axis: #c3c2b7;
  --border: rgba(11, 11, 11, 0.10);
  --wash: rgba(11, 11, 11, 0.035);
  --cf: #2a78d6;
  --ref: #eb6834;
  --base: #898781;
  --accent: #2a78d6;
  --accent-ink: #ffffff;
  --error: #b3261e;
  --radius: 8px;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --page: #0d0d0d;
    --surface: #1a1a19;
    --ink: #ffffff;
    --ink-2: #c3c2b7;
    --muted: #898781;
    --grid: #2c2c2a;
    --axis: #383835;
    --border: rgba(255, 255, 255, 0.10);
    --wash: rgba(255, 255, 255, 0.04);
    --cf: #3987e5;
    --ref: #d95926;
    --base: #9a9890;
    --accent: #3987e5;
    --error: #f2877f;
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #0d0d0d;
  --surface: #1a1a19;
  --ink: #ffffff;
  --ink-2: #c3c2b7;
  --muted: #898781;
  --grid: #2c2c2a;
  --axis: #383835;
  --border: rgba(255, 255, 255, 0.10);
  --wash: rgba(255, 255, 255, 0.04);
  --cf: #3987e5;
  --ref: #d95926;
  --base: #9a9890;
  --accent: #3987e5;
  --error: #f2877f;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-size: 15px;
  line-height: 1.45;
}
h1, h2, h3 { line-height: 1.2; margin: 0; }

header.site, main, .about, .disclaimer {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 16px;
}
header.site { padding-top: 16px; padding-bottom: 8px; }
.lede { color: var(--ink-2); margin: 8px 0 0; }
.lede a { color: var(--accent); }

main {
  display: grid;
  grid-template-columns: 320px minmax(0, 1fr);
  gap: 20px;
  padding-top: 16px;
  padding-bottom: 16px;
  align-items: start;
}
@media (max-width: 860px) {
  main { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- controls ---------- */
.controls {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4px 16px;
}
@media (min-width: 861px) {
  .controls { position: sticky; top: 12px; }
}
.controls section { padding: 12px 0; border-top: 1px solid var(--grid); }
.controls section:first-child { border-top: 0; }
.field { display: grid; gap: 4px; font-size: 0.85rem; color: var(--ink-2); margin-bottom: 10px; }
.field:last-child { margin-bottom: 0; }
.field.inline { display: flex; align-items: center; gap: 8px; margin: 0; }
select, button {
  font: inherit;
  color: var(--ink);
  background: var(--page);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
}
select { width: 100%; }
.field.inline select { width: auto; }
button { cursor: pointer; }
button:hover { background: var(--wash); }
button:focus-visible, select:focus-visible, input:focus-visible, svg:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.segmented { border: 0; padding: 0; margin: 0 0 12px; display: flex; gap: 0; flex-wrap: wrap; }
.segmented legend { font-size: 0.85rem; color: var(--ink-2); margin-bottom: 4px; padding: 0; }
.segmented label {
  flex: 1;
  text-align: center;
  font-size: 0.9rem;
  padding: 6px 8px;
  border: 1px solid var(--border);
  cursor: pointer;
  background: var(--page);
}
.segmented label:first-of-type { border-radius: 6px 0 0 6px; }
.segmented label:last-of-type { border-radius: 0 6px 6px 0; border-left: 0; }
.segmented input { position: absolute; opacity: 0; pointer-events: none; }
.segmented label:has(input:checked) { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.segmented label:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }

.formula {
  font-family: "Times New Roman", Times, serif;
  font-style: italic;
  font-size: 0.98rem;
  color: var(--ink-2);
  background: var(--wash);
  border-radius: 6px;
  padding: 8px 10px;
  margin: 0 0 10px;
}
.formula > span { white-space: nowrap; }
.presets { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 8px; }
.presets button { font-size: 0.82rem; padding: 4px 8px; }
.presets button[aria-pressed="true"] { border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }

.slider { display: grid; gap: 2px; margin: 8px 0; font-size: 0.88rem; }
.slider > span { display: flex; justify-content: space-between; gap: 8px; }
.slider output { font-variant-numeric: tabular-nums; font-weight: 600; }
input[type="range"] { width: 100%; accent-color: var(--accent); margin: 2px 0; }
input[type="range"]:disabled { opacity: 0.4; }
.hint { font-size: 0.8rem; color: var(--ink-2); margin: 6px 0 0; }
.check { display: flex; gap: 8px; align-items: center; font-size: 0.9rem; }
.check input { accent-color: var(--accent); width: 16px; height: 16px; }
.row { display: flex; justify-content: space-between; align-items: center; gap: 8px; }
.ghost { background: transparent; }

/* ---------- results ---------- */
.results { min-width: 0; }
.status { margin: 0 0 8px; min-height: 1.45em; font-size: 0.88rem; color: var(--ink-2); }
.status[data-kind="error"] { color: var(--error); font-weight: 600; }
.charts { display: grid; gap: 12px; transition: opacity 0.15s; }
body.busy .charts { opacity: 0.6; }
.panel {
  margin: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 12px 4px;
}
.panel figcaption { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline; gap: 4px 12px; }
.panel h3 { font-size: 0.95rem; font-weight: 600; }
.panel-legend { display: flex; flex-wrap: wrap; gap: 4px 12px; font-size: 0.8rem; color: var(--ink-2); }
.key { display: inline-flex; align-items: center; gap: 5px; }
.plot { position: relative; height: 210px; }
@media (max-width: 520px) { .plot { height: 180px; } }
.plot svg { display: block; width: 100%; height: 100%; touch-action: pan-y; }

.grid { stroke: var(--grid); stroke-width: 1; }
.axis { stroke: var(--axis); stroke-width: 1; }
.tick { fill: var(--muted); font-size: 11px; font-variant-numeric: tabular-nums; }
.projection { fill: var(--wash); }
.proj-label { fill: var(--muted); font-size: 11px; }
.mark-rule { stroke: var(--muted); stroke-width: 1; stroke-dasharray: 1.5 3; stroke-linecap: round; }
.hline { stroke: var(--muted); stroke-width: 1; }
.hline-label { fill: var(--muted); font-size: 10px; }
.series { fill: none; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.series.cf { stroke: var(--cf); stroke-width: 2.5; }
.series.base { stroke: var(--base); }
.series.ref { stroke: var(--ref); stroke-dasharray: 5 4; stroke-linecap: butt; }
.crosshair { stroke: var(--muted); stroke-width: 1; }
.dot { stroke: var(--surface); stroke-width: 2; }
.dot.cf { fill: var(--cf); }
.dot.base { fill: var(--base); }
.dot.ref { fill: var(--ref); }
.hit { fill: transparent; cursor: crosshair; }

.tooltip {
  position: absolute;
  top: 6px;
  pointer-events: none;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
  padding: 6px 8px;
  font-size: 0.8rem;
  white-space: nowrap;
  z-index: 2;
}
.tip-date { color: var(--ink-2); margin-bottom: 2px; }
.tip-row { display: flex; align-items: center; gap: 6px; }
.tip-row strong { font-variant-numeric: tabular-nums; min-width: 3.2em; }
.tip-row span { color: var(--ink-2); }

.note { font-size: 0.8rem; color: var(--ink-2); margin: 8px 0; }
.actions { display: flex; flex-wrap: wrap; gap: 8px; }

/* ---------- about ---------- */
.about { padding-top: 8px; padding-bottom: 40px; color: var(--ink-2); max-width: 1180px; }
.about h2 { font-size: 1.1rem; color: var(--ink); margin: 8px 0; }
.about p { max-width: none; }
.about a { color: var(--accent); }
.cite { font-size: 0.85rem; }
.about sup { line-height: 0; }
.about sup a { text-decoration: none; }
.footnotes {
  max-width: none;
  font-size: 0.82rem;
  color: var(--ink-2);
  padding-left: 1.4em;
  margin: 14px 0;
}
.footnotes li { margin: 4px 0; }
.fn-back { margin-left: 4px; }

/* ---------- edit mode ---------- */
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.segmented.modes { margin: 14px 0 0; max-width: 420px; }
.hint.first { margin-top: 0; }
.sub { font-size: 0.85rem; color: var(--ink-2); margin: 12px 0 4px; }
.levels { display: grid; gap: 6px; }
.levels label { display: flex; justify-content: space-between; align-items: center; gap: 8px; font-size: 0.88rem; }
.levels input {
  width: 5.5em; font: inherit; color: var(--ink); background: var(--page);
  border: 1px solid var(--border); border-radius: 6px; padding: 4px 6px; text-align: right;
}

.editable .hit { cursor: ns-resize; }
.editable svg { touch-action: none; }
.editable .panel { outline: 1px dashed var(--accent); outline-offset: -1px; }
.brush { display: flex; align-items: center; gap: 10px; margin: 0 0 8px; font-size: 0.85rem; color: var(--ink-2); }
.brush .presets { margin: 0; }
.brush[hidden] { display: none; }

.disclaimer { padding-top: 12px; padding-bottom: 32px; color: var(--ink-2); font-size: 0.8rem; }
.disclaimer p { margin: 0; padding-top: 12px; border-top: 1px solid var(--grid); }

.edit-buttons { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 10px; }
.edit-buttons button:disabled { opacity: 0.45; cursor: default; }
.notice {
  margin: 0 0 10px; padding: 8px 12px; font-size: 0.85rem; color: var(--ink);
  background: var(--wash); border-left: 3px solid var(--ref); border-radius: 4px;
}

.symbols { margin: -4px 0 10px; font-size: 0.8rem; color: var(--ink-2); }
.symbols summary { cursor: pointer; }
.symbols dl { display: grid; grid-template-columns: max-content 1fr; gap: 4px 10px; margin: 8px 0 0; }
.symbols dt { font-family: "Times New Roman", Times, serif; font-style: italic; color: var(--ink); white-space: nowrap; }
.symbols dd { margin: 0; }