/* Dynamic State Variable Model builder.
   Palette: petrol ink on limestone, one teal accent, claret for errors,
   dark gold for warnings. Type: Spectral for headings and the equation,
   IBM Plex Sans for the interface, IBM Plex Mono for expressions. */

:root {
  --ink: #10242e;
  --ink-soft: #3d555f;
  --ink-faint: #6b8189;
  --paper: #edf1f0;
  --panel: #ffffff;
  --rule: #c3cfd0;
  --rule-soft: #dde5e4;
  --accent: #0e6e78;
  --accent-dark: #0a5259;
  --accent-wash: #e2eeef;
  --claret: #9e1b3c;
  --claret-wash: #fbeaee;
  --gold: #7e5e08;
  --gold-wash: #fbf2dc;
  --serif: "Spectral", "Iowan Old Style", Georgia, "Times New Roman", serif;
  --sans: "IBM Plex Sans", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: "IBM Plex Mono", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --radius: 3px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 16px/1.55 var(--sans);
}

.wrap { max-width: 1140px; margin: 0 auto; padding: 0 20px; }

a { color: var(--accent-dark); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--claret); }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.hidden { display: none !important; }

/* ------------------------------------------------------------ masthead */

.masthead { background: var(--ink); color: #eef4f4; padding: 26px 0 0; }

.masthead-inner {
  display: flex;
  gap: 28px;
  align-items: flex-start;
  justify-content: space-between;
  padding-bottom: 20px;
}

.masthead h1 {
  font: 600 clamp(26px, 3.4vw, 40px)/1.1 var(--serif);
  margin: 0 0 6px;
  letter-spacing: -0.012em;
}

.subtitle {
  margin: 0;
  max-width: 58ch;
  color: #a9c2c4;
  font-size: 15px;
}

.lattice { width: 132px; height: 64px; flex: none; margin-top: 6px; }
.lattice circle { fill: #2f4d57; }
.lattice circle.on { fill: #6fb3ba; }
.lattice-path { fill: none; stroke: #6fb3ba; stroke-width: 1.6; stroke-linejoin: round; }

/* ------------------------------------------------------------- toolbar */

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  padding-top: 14px;
  padding-bottom: 14px;
  border-top: 1px solid #27414b;
}

.toolbar .field.inline span { color: #a9c2c4; }
.toolbar-note { color: #8fb0b3; font-size: 13.5px; }

/* --------------------------------------------------------------- cards */

main { padding: 26px 0 40px; }

.card {
  position: relative;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 22px 24px 24px;
  margin: 0 0 20px;
}

.card[data-num]::before {
  content: attr(data-num);
  position: absolute;
  left: -44px;
  top: 22px;
  width: 30px;
  text-align: right;
  font: 600 20px/1 var(--serif);
  color: var(--ink-faint);
}

.card > h2 {
  font: 600 22px/1.2 var(--serif);
  margin: 0 0 4px;
}

.card h3 {
  font: 600 17px/1.3 var(--serif);
  margin: 28px 0 4px;
  padding-bottom: 5px;
  border-bottom: 1px solid var(--rule-soft);
}

.hint { margin: 4px 0 14px; color: var(--ink-soft); font-size: 14px; max-width: 78ch; }
.hint:last-child { margin-bottom: 0; }

/* --------------------------------------------------------------- forms */

.field { display: block; margin: 0 0 12px; }
.field > span { display: block; font-size: 13.5px; color: var(--ink-soft); margin-bottom: 4px; }
.field.inline { display: inline-flex; align-items: center; gap: 8px; margin: 0; }
.field.inline > span { margin: 0; white-space: nowrap; }

input[type="text"], input[type="number"], select, textarea {
  width: 100%;
  font: 400 15px/1.4 var(--sans);
  color: var(--ink);
  background: #fff;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 7px 9px;
}

textarea { resize: vertical; }
select { padding: 6px 8px; }
.field.inline select, .field.inline input { width: auto; }

input.mono, textarea.mono { font-family: var(--mono); font-size: 14px; }

input:focus, select:focus, textarea:focus { border-color: var(--accent); outline-offset: 1px; }

input.invalid, textarea.invalid { border-color: var(--claret); background: var(--claret-wash); }

em.err {
  display: none;
  font-style: normal;
  font-size: 13px;
  color: var(--claret);
  margin-top: 4px;
  font-family: var(--mono);
  line-height: 1.4;
}
em.err.shown { display: block; }

label.check { display: flex; align-items: flex-start; gap: 8px; font-size: 14px; margin: 6px 0 12px; }
label.check input { width: auto; margin-top: 3px; flex: none; }

.grid2 { display: grid; grid-template-columns: 2fr 1fr; gap: 0 18px; }
.grid3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0 18px; }
.grid4 { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0 18px; }

fieldset { border: 0; padding: 0; margin: 0; min-width: 0; }
fieldset[disabled] { opacity: 0.55; }

/* ------------------------------------------------------------- buttons */

.btn {
  font: 500 14.5px/1 var(--sans);
  color: var(--ink);
  background: #f3f6f6;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 9px 14px;
  cursor: pointer;
}
.btn:hover { background: var(--accent-wash); border-color: var(--accent); }
.btn:disabled { cursor: not-allowed; opacity: 0.5; background: #f3f6f6; border-color: var(--rule); }

.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { background: var(--accent-dark); border-color: var(--accent-dark); }
.btn.primary:disabled { background: var(--ink-faint); border-color: var(--ink-faint); }

.btn.quiet { background: transparent; }
.btn.small { padding: 5px 9px; font-size: 13px; }
.btn.icon { padding: 5px 8px; font-family: var(--mono); }

.file-btn { position: relative; overflow: hidden; display: inline-block; }
.file-btn input[type="file"] { position: absolute; inset: 0; opacity: 0; cursor: pointer; width: 100%; }

.row-actions { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-top: 12px; }

.metric { font-size: 14px; color: var(--ink-soft); }
.metric strong { color: var(--ink); font-weight: 500; }

/* ------------------------------------------------------ repeated items */

.item-list { display: flex; flex-direction: column; gap: 14px; margin-bottom: 4px; }

.item {
  border: 1px solid var(--rule-soft);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 14px 16px 6px;
  background: #fbfcfc;
}

.item-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}

.item-title { font: 600 15px/1.3 var(--serif); margin: 0; }
.item-title span { font-family: var(--mono); font-weight: 400; font-size: 13.5px; color: var(--ink-faint); }
.item-tools { display: flex; gap: 6px; flex: none; }

.outcome {
  border-top: 1px solid var(--rule-soft);
  padding-top: 10px;
  margin-top: 8px;
}
.outcome-head { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; }
.outcome-head h5 { font: 600 13.5px/1.3 var(--sans); margin: 0 0 6px; color: var(--ink-soft); }

details.advanced { margin: 4px 0 10px; }
details.advanced > summary,
#exprHelp > summary {
  cursor: pointer;
  font-size: 14px;
  color: var(--accent-dark);
  padding: 4px 0;
}
details.advanced[open] > summary { margin-bottom: 8px; }

.help-body { font-size: 14.5px; max-width: 80ch; }
.help-body h3 { font: 600 15px/1.3 var(--serif); border: 0; margin: 16px 0 2px; padding: 0; }
.help-body ul { margin: 4px 0; padding-left: 22px; }
.help-body li { margin-bottom: 3px; }

code { font: 400 13.5px/1.4 var(--mono); background: var(--accent-wash); padding: 1px 4px; border-radius: 2px; }

.probsum { font-size: 13px; font-family: var(--mono); color: var(--ink-soft); }
.probsum.bad { color: var(--claret); font-weight: 500; }

/* -------------------------------------------------------------- alerts */

.alert {
  border: 1px solid;
  border-left-width: 4px;
  border-radius: var(--radius);
  padding: 11px 14px;
  margin: 14px 0;
  font-size: 14.5px;
}
.alert.error { border-color: var(--claret); background: var(--claret-wash); color: #6d1229; }
.alert.warn { border-color: var(--gold); background: var(--gold-wash); color: #5c4406; }
.alert strong { display: block; margin-bottom: 3px; font-weight: 600; }
.alert .detail { font-family: var(--mono); font-size: 13.5px; line-height: 1.5; white-space: pre-wrap; word-break: break-word; }
.alert ul { margin: 4px 0 0; padding-left: 20px; }
.alert li { font-family: var(--mono); font-size: 13px; }

/* ------------------------------------------------------------ equation */

.equation {
  font-family: var(--serif);
  font-size: 18px;
  line-height: 2;
  background: #fbfcfc;
  border: 1px solid var(--rule-soft);
  border-left: 3px solid var(--ink);
  border-radius: var(--radius);
  padding: 18px 20px;
  overflow-x: auto;
}
.equation .line { margin-bottom: 8px; white-space: nowrap; }
.equation .line:last-child { margin-bottom: 0; }
.equation .v { font-style: italic; }
.equation .op { padding: 0 3px; color: var(--ink-soft); }
.equation .src { font-family: var(--mono); font-style: normal; font-size: 14px; color: var(--accent-dark); }
.equation .aname { font-family: var(--sans); font-style: normal; font-size: 15px; }
.equation sub, .equation sup { font-size: 0.66em; }
.equation .note { font-family: var(--sans); font-size: 14px; line-height: 1.5; color: var(--ink-soft); white-space: normal; }
.equation .big { font-size: 1.25em; }

/* -------------------------------------------------------------- tables */

.table-scroll {
  max-height: 420px;
  overflow: auto;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  margin: 12px 0;
}

table { border-collapse: separate; border-spacing: 0; font-size: 13px; width: max-content; min-width: 100%; }
table th, table td { padding: 4px 9px; text-align: right; white-space: nowrap; border-bottom: 1px solid var(--rule-soft); }
table thead th {
  position: sticky; top: 0; z-index: 2;
  background: #eff3f3; font-weight: 500; font-size: 12.5px;
  border-bottom: 1px solid var(--rule);
}
table tbody th {
  position: sticky; left: 0; z-index: 1;
  background: #f7f9f9; font-weight: 500; font-family: var(--mono); font-size: 12.5px;
}
table td.num { font-family: var(--mono); }
table td.dead { color: var(--ink-faint); background: #f4f6f6; }
table tbody tr:hover td { background: var(--accent-wash); }

/* --------------------------------------------------------------- plots */

/* An explicit height matters: Plotly sizes itself from the container, and a
   container shorter than the plot margins makes its axis scaling fail. */
.plot { width: 100%; height: 460px; margin: 10px 0 4px; }
@media (max-width: 860px) { .plot { height: 380px; } }

.view-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: center;
  margin: 12px 0 6px;
  padding: 10px 12px;
  background: #f5f8f8;
  border: 1px solid var(--rule-soft);
  border-radius: var(--radius);
}
.view-controls .field.inline span { font-size: 13px; }

.swatches { display: flex; flex-wrap: wrap; gap: 6px 16px; margin: 8px 0 4px; font-size: 13.5px; }
.swatches span { display: inline-flex; align-items: center; gap: 6px; }
.swatches i { width: 13px; height: 13px; border-radius: 2px; border: 1px solid rgba(0, 0, 0, 0.18); flex: none; }

.headline {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 1px;
  background: var(--rule-soft);
  border: 1px solid var(--rule-soft);
  border-radius: var(--radius);
  margin: 6px 0 4px;
  overflow: hidden;
}
.headline div { background: var(--panel); padding: 11px 14px; }
.headline dt { font-size: 13px; color: var(--ink-soft); margin: 0 0 3px; }
.headline dd { margin: 0; font: 600 21px/1.15 var(--serif); font-variant-numeric: tabular-nums; }
.headline dd small { font: 400 13px/1.3 var(--sans); color: var(--ink-soft); display: block; margin-top: 3px; }

/* -------------------------------------------------------------- footer */

.footer {
  border-top: 1px solid var(--rule);
  background: #e3e9e8;
  padding: 22px 0 34px;
  font-size: 14px;
  color: var(--ink-soft);
}
.footer p { margin: 0 0 8px; max-width: 86ch; }
.footnote { font-size: 13.5px; }

/* ------------------------------------------------------------ narrower */

@media (max-width: 1260px) {
  .card[data-num]::before {
    position: static;
    display: inline-block;
    width: auto;
    margin-right: 8px;
    font-size: 17px;
  }
  .card > h2 { display: inline; }
  .card > h2 + * { margin-top: 12px; }
}

@media (max-width: 860px) {
  .grid2, .grid3, .grid4 { grid-template-columns: 1fr; }
  .masthead-inner { flex-direction: column; }
  .lattice { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

/* --------------------------------------------- equation parameter tables */

#equationTables {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(330px, 1fr));
  gap: 14px;
  margin-top: 16px;
}

.eqblock {
  border: 1px solid var(--rule-soft);
  border-radius: var(--radius);
  padding: 12px 14px 14px;
  background: #fbfcfc;
  min-width: 0;
}
.eqblock h4 {
  font: 600 15px/1.3 var(--serif);
  margin: 0 0 4px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.eqswatch { width: 11px; height: 11px; border-radius: 2px; flex: none; }
.eqmeta { font-size: 13.5px; color: var(--ink-soft); margin: 0 0 8px; }
.eqmeta .src { font-family: var(--mono); font-size: 13px; color: var(--accent-dark); }

.eqtable { width: 100%; font-size: 13px; }
.eqtable th, .eqtable td { border-bottom: 1px solid var(--rule-soft); padding: 4px 8px 4px 0; white-space: normal; }
.eqtable thead th { position: static; background: none; border-bottom: 1px solid var(--rule); font-size: 12.5px; color: var(--ink-soft); }
.eqtable tbody tr:last-child td { border-bottom: 0; }
.eqtable tbody tr:hover td { background: none; }
.lft { text-align: left; }
.eqtable .src { font-family: var(--mono); font-size: 12.5px; color: var(--accent-dark); }

/* -------------------------------------------------------- range + output */

.view-controls input[type="range"] { width: 170px; vertical-align: middle; accent-color: var(--accent); }
.view-controls output { display: inline-block; min-width: 2.2em; font-family: var(--mono); text-align: right; }

/* ------------------------------------------------------------ refinements */

.toolbar .btn { background: #1c333d; border-color: #3a545e; color: #dfeaea; }
.toolbar .btn:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
.toolbar .btn.quiet { background: transparent; color: #a9c2c4; }
.toolbar .btn.quiet:hover { background: #1c333d; color: #dfeaea; border-color: #3a545e; }

.probsum.prose { font-family: var(--sans); }

.swatches .plain { color: var(--ink-soft); }

.headline { background: var(--panel); }
.headline div { box-shadow: 0 0 0 1px var(--rule-soft); }