/* =====================================================================
   ConvCalcs - shared stylesheet for all calculators
   ---------------------------------------------------------------------
   Visual style: "high-performance HMI" (ISA-101 inspired).
     - Neutral greys everywhere; colour only means something
       (blue = selected / editable focus, yellow = warning, red = error,
       green = OK status).
     - Panels have dark title bars, inputs are white sunken fields,
       results are recessed read-out boxes with monospaced digits.

   Page building blocks (reuse these on every calculator page):
     .site-header / .site-footer   top and bottom bars
     .page-head                    breadcrumb + h1 + lead
     .calc-layout                  inputs column | output column
     .panel + .panel-head + .panel-body
     .param                        one parameter row: label | value box
     .input-unit                   value box with unit (or unit select)
     .segmented / .mode-toggle     HMI style toggle buttons
     .kpis / .kpi                  headline read-outs
     .results-list                 secondary read-outs
     .notes / .note                warning (yellow) / error (red) banners
     .formula-table                calculation steps table
     .info-grid / .prose           explanation sections
     .contact                      call-to-action banner
   ===================================================================== */

:root {
  /* Surfaces */
  --bg: #cfd3d7;            /* page background */
  --panel: #e3e6e9;         /* panel body */
  --panel-2: #d8dce0;       /* subtle bands, table header */
  --title: #3a424b;         /* panel title bars */
  --chrome: #23292f;        /* site header */
  --canvas: #eef0f2;        /* drawing background */
  --field: #ffffff;         /* editable input */
  --readout: #f5f6f7;       /* read-only value box */

  /* Lines */
  --line: #b9c0c7;
  --line-strong: #8e969f;

  /* Text */
  --text: #1a1f24;
  --text-2: #37404a;
  --muted: #5e6873;

  /* Meaningful colour only */
  --select: #2f6aa8;        /* selected toggle / focus */
  --select-soft: rgba(47, 106, 168, 0.18);
  --ok: #2e8540;
  --warn: #f2c200;
  --warn-bg: #fff3bf;
  --warn-text: #3b3000;
  --alarm: #c62828;
  --alarm-bg: #fbe3e3;
  --alarm-text: #7a1010;

  /* Illustration (muted process-graphic greys) */
  --svg-frame: #7c848d;
  --svg-belt: #2a2f35;
  --svg-pulley: #aab1b9;
  --svg-pulley-hub: #2a2f35;
  --svg-box: #c7b48d;
  --svg-box-edge: #8d7a52;
  --svg-motor: #5a6b7c;
  --svg-gearbox: #73859a;
  --svg-chain: #8b4f3a;
  --svg-arrow: #2f6aa8;
  --svg-force: #b03030;
  --svg-floor: #8e969f;

  --radius: 3px;
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "Cascadia Mono", "Consolas", "Roboto Mono", ui-monospace, "SFMono-Regular", monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--select); }
h1, h2, h3 { line-height: 1.25; margin: 0; }
[hidden] { display: none !important; }

.container { max-width: 1240px; margin: 0 auto; padding: 0 12px; }
@media (min-width: 720px) { .container { padding: 0 20px; } }

/* ---------- Header / footer ---------- */
.site-header { background: var(--chrome); color: #fff; border-bottom: 3px solid var(--title); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 46px; gap: 16px; }
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: #fff; text-decoration: none; font-weight: 700; font-size: 0.95rem; letter-spacing: 0.04em;
}
.brand-mark {
  display: inline-grid; place-items: center;
  width: 24px; height: 24px; border-radius: 2px;
  background: #4b555f; border: 1px solid #6b7580;
  color: #fff; font-size: 0.66rem; font-weight: 800;
}
.site-nav { display: flex; gap: 2px; }
.site-nav a {
  color: #c9d0d7; text-decoration: none; font-size: 0.82rem; letter-spacing: 0.03em;
  padding: 5px 10px; border-radius: var(--radius);
}
.site-nav a:hover { color: #fff; background: #3a424b; }
@media (max-width: 420px) { .site-nav a:not(:first-child) { display: none; } }

.site-footer { margin-top: 24px; background: var(--chrome); color: #aeb6be; font-size: 0.78rem; }
.footer-inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px; padding-top: 12px; padding-bottom: 12px; }

/* ---------- Page head ---------- */
main { padding: 14px 0 4px; }
.page-head { margin-bottom: 12px; }
.breadcrumb { font-size: 0.78rem; color: var(--muted); margin-bottom: 4px; }
.breadcrumb a { color: var(--muted); text-decoration: none; }
.breadcrumb a:hover { color: var(--select); }
.breadcrumb span { margin: 0 6px; }
h1 { font-size: clamp(1.25rem, 2.6vw, 1.6rem); font-weight: 700; color: var(--text); }
.lead { color: var(--text-2); margin: 4px 0 0; max-width: 90ch; font-size: 0.9rem; }

/* ---------- Panels ---------- */
.panel, .card {
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
}
.panel-head {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  min-height: 34px; padding: 4px 6px 4px 12px;
  background: var(--title); color: #fff;
  border-radius: var(--radius) var(--radius) 0 0;
}
.panel-head h2 { font-size: 0.76rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; }
.panel-meta { font-size: 0.74rem; color: #c9d0d7; display: inline-flex; align-items: center; gap: 6px; padding-right: 6px; font-family: var(--mono); }
.panel-body { padding: 12px; }

.status-dot { width: 9px; height: 9px; border-radius: 50%; background: var(--ok); border: 1px solid rgba(0, 0, 0, 0.35); }
.status-dot.warn { background: var(--warn); }
.status-dot.alarm { background: var(--alarm); }

.link-btn {
  background: none; border: 0; padding: 0; font: inherit; font-size: 0.8rem;
  color: var(--select); cursor: pointer; text-align: left;
}
.link-btn:hover { text-decoration: underline; }

/* ---------- Calculator layout ----------
   Desktop: inputs | (drawing + results). Both columns stretch to the same
   height; the drawing absorbs the difference so there are no gaps. */
.calc-layout { display: grid; gap: 12px; grid-template-columns: minmax(0, 1fr); }
.output-col { display: flex; flex-direction: column; gap: 12px; min-width: 0; }
.inputs-panel { display: flex; flex-direction: column; }
.inputs-panel .panel-body { flex: 1; display: flex; flex-direction: column; }
@media (min-width: 1080px) {
  .calc-layout { grid-template-columns: 390px minmax(0, 1fr); align-items: stretch; }
}

/* ---------- HMI toggle buttons (mode + drive type) ---------- */
.mode-toggle, .segmented {
  display: inline-grid; grid-auto-flow: column; grid-auto-columns: 1fr;
  background: #2b3238; border: 1px solid #1d2227; border-radius: var(--radius); padding: 2px; gap: 2px;
}
.mode-toggle button, .segmented span {
  display: block; padding: 4px 12px;
  font: inherit; font-size: 0.76rem; font-weight: 600; letter-spacing: 0.04em; text-transform: uppercase;
  color: #c9d0d7; background: transparent; border: 0; border-radius: 2px; cursor: pointer; text-align: center;
}
.mode-toggle button:hover, .segmented label:hover span { color: #fff; }
.mode-toggle button[aria-pressed="true"], .segmented input:checked + span { background: var(--select); color: #fff; }
.mode-toggle button:focus-visible, .segmented input:focus-visible + span { outline: 2px solid #fff; outline-offset: -2px; }

/* Drive type toggle lives inside the panel body: light variant, same width as value boxes */
.segmented { width: 100%; background: var(--panel-2); border-color: var(--line-strong); }
.segmented label { margin: 0; cursor: pointer; position: relative; }
.segmented input { position: absolute; opacity: 0; pointer-events: none; }
.segmented span { color: var(--text-2); padding: 7px 6px; }
.segmented label:hover span { color: var(--text); }

/* ---------- Parameter rows (label left, value box right, all boxes equal) ---------- */
fieldset { border: 0; margin: 0; padding: 0; min-width: 0; }
legend {
  display: block; width: 100%; padding: 0 0 4px; margin-bottom: 4px;
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted);
  border-bottom: 1px solid var(--line);
}
.field-group + .field-group { margin-top: 14px; }

.param {
  display: grid; grid-template-columns: minmax(0, 1fr) 176px; align-items: center; gap: 10px;
  padding: 4px 0;
}
.param > label, .param > .label { font-size: 0.85rem; color: var(--text-2); font-weight: 600; line-height: 1.25; }
.param .sub { display: block; font-weight: 400; font-size: 0.74rem; color: var(--muted); }
.param-slider { padding: 0 0 4px; }
.param-slider input[type="range"] { width: 100%; margin: 4px 0 0; accent-color: var(--select); }

/* Advanced-only rows are hidden in Basic mode */
.mode-basic [data-adv] { display: none !important; }
.inputs-panel:not(.mode-basic) #basicNote { display: none; }

/* Value box: white sunken field with the unit (or a unit selector) on the right */
.input-unit {
  display: flex; align-items: stretch;
  height: 34px; width: 100%;
  background: var(--field);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.18);
}
.input-unit:focus-within { border-color: var(--select); box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.18), 0 0 0 2px var(--select-soft); }
.input-unit input {
  flex: 1; min-width: 0; height: 100%;
  border: 0; background: transparent; outline: none;
  padding: 0 6px 0 9px; text-align: right;
  font-family: var(--mono); font-size: 0.92rem; color: var(--text);
  -moz-appearance: textfield;
}
.input-unit input::-webkit-outer-spin-button,
.input-unit input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.input-unit .unit, .input-unit .unit-select {
  flex: none; width: 66px; display: flex; align-items: center; padding: 0 8px;
  font-size: 0.76rem; color: var(--muted);
  background: var(--panel-2); border-left: 1px solid var(--line);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.input-unit .unit-select {
  border: 0; border-left: 1px solid var(--line); font-family: inherit; color: var(--text-2); font-weight: 600; cursor: pointer;
  -webkit-appearance: none; appearance: none; padding: 0 14px 0 7px;
  background: var(--panel-2) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='8' height='5'%3E%3Cpath d='M0 0l4 5 4-5z' fill='%2337404a'/%3E%3C/svg%3E") no-repeat right 6px center;
}
.input-unit .unit-select:focus { outline: none; color: var(--select); }
.input-unit:has(input.invalid) { border-color: var(--alarm); background: var(--alarm-bg); }

.param-select {
  width: 100%; height: 34px; padding: 0 24px 0 9px;
  font: inherit; font-size: 0.84rem; color: var(--text);
  background: var(--field) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='8' height='5'%3E%3Cpath d='M0 0l4 5 4-5z' fill='%2337404a'/%3E%3C/svg%3E") no-repeat right 9px center;
  border: 1px solid var(--line-strong); border-radius: var(--radius);
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.18);
  -webkit-appearance: none; appearance: none;
}
.param-select:focus { outline: none; border-color: var(--select); box-shadow: 0 0 0 2px var(--select-soft); }

/* Basic mode assumptions box + reset link pinned to the bottom of the panel */
.assumptions {
  margin-top: 14px; padding: 10px 12px;
  background: var(--panel-2); border: 1px dashed var(--line-strong); border-radius: var(--radius);
  font-size: 0.82rem; color: var(--text-2);
}
.assumptions ul { margin: 6px 0 8px; padding-left: 18px; }
.form-foot { margin-top: auto; padding-top: 12px; text-align: right; }

/* ---------- Illustration ---------- */
.illustration { margin: 0; display: flex; flex-direction: column; flex: 1 1 auto; }
.svg-wrap {
  position: relative; background: var(--canvas);
  flex: 1 1 auto; min-height: 230px;
  border-radius: 0 0 var(--radius) var(--radius);
}
.svg-wrap svg { position: absolute; inset: 0; width: 100%; height: 100%; display: block; }
@media (max-width: 1079px) {
  .svg-wrap { flex: none; min-height: 0; aspect-ratio: 16 / 7; }
}

/* SVG drawing classes */
.svg-floor { stroke: var(--svg-floor); stroke-width: 3; }
.svg-floor.thin { stroke-width: 1.5; }
.svg-frame { fill: var(--svg-frame); }
.svg-belt { fill: none; stroke: var(--svg-belt); stroke-width: 5; stroke-linejoin: round; }
.svg-pulley { fill: var(--svg-pulley); stroke: var(--svg-belt); stroke-width: 1.5; }
.svg-hub { fill: var(--svg-pulley-hub); }
.svg-hub.light { fill: var(--canvas); stroke: var(--svg-pulley-hub); stroke-width: 2; }
.svg-box { fill: var(--svg-box); stroke: var(--svg-box-edge); stroke-width: 1.5; }
.svg-box-tape { stroke: var(--svg-box-edge); stroke-width: 1.5; opacity: 0.6; }
.svg-gearbox { fill: var(--svg-gearbox); stroke: var(--svg-motor); stroke-width: 1.5; }
.svg-motor { fill: var(--svg-motor); }
.svg-fin { stroke: rgba(255, 255, 255, 0.3); stroke-width: 2; }
.svg-sprocket { fill: var(--canvas); stroke: var(--svg-pulley-hub); stroke-width: 1.5; }
.svg-sprocket-teeth { fill: none; stroke: var(--svg-chain); stroke-width: 4; stroke-dasharray: 3 3; }
.svg-chain { stroke: var(--svg-chain); stroke-width: 3; stroke-dasharray: 5 2; }
.svg-arrow { stroke: var(--svg-arrow); stroke-width: 3; }
.svg-force { stroke: var(--svg-force); stroke-width: 3.5; }
.svg-dim { fill: none; stroke: var(--muted); stroke-width: 1.5; stroke-dasharray: 6 5; }
.svg-dim.solid { stroke-dasharray: none; }
.marker-blue { fill: var(--svg-arrow); }
.marker-red { fill: var(--svg-force); }
.svg-label { fill: var(--text); font-family: var(--font); font-size: 20px; }
.svg-label.strong { font-weight: 700; }
.svg-label.small { font-size: 16px; fill: var(--muted); }
.svg-label.blue { fill: var(--svg-arrow); font-weight: 600; }
.svg-label.red { fill: var(--svg-force); font-weight: 700; }
.svg-label.chain { fill: var(--svg-chain); }

/* ---------- Results: KPI read-outs ---------- */
.kpis { display: grid; gap: 8px; grid-template-columns: repeat(2, minmax(0, 1fr)); margin-bottom: 10px; }
@media (min-width: 620px) { .kpis { grid-template-columns: repeat(4, minmax(0, 1fr)); } }
.kpi {
  display: flex; flex-direction: column; gap: 2px; min-width: 0;
  padding: 8px 10px;
  background: var(--readout);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.12);
}
.kpi-label { font-size: 0.7rem; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; }
.kpi-value { font-family: var(--mono); font-size: 1.45rem; font-weight: 700; line-height: 1.2; white-space: nowrap; color: var(--text); }
.kpi-value small { font-family: var(--font); font-size: 0.76rem; font-weight: 600; color: var(--muted); margin-left: 4px; }
.kpi-sub { font-size: 0.72rem; color: var(--muted); }
/* Primary read-out: dark display panel */
.kpi.primary { background: #1f252b; border-color: #11151a; box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.5); }
.kpi.primary .kpi-label, .kpi.primary .kpi-sub { color: #9aa4ae; }
.kpi.primary .kpi-value { color: #ffffff; }
.kpi.primary .kpi-value small { color: #9aa4ae; }

/* ---------- Results: secondary read-outs ---------- */
.results-list { margin: 0; display: grid; grid-template-columns: minmax(0, 1fr); column-gap: 20px; }
@media (min-width: 560px) { .results-list { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.results-list .row { display: flex; justify-content: space-between; align-items: center; gap: 10px; padding: 3px 0; }
.results-list dt { color: var(--text-2); font-size: 0.84rem; }
.results-list dd {
  margin: 0; min-width: 118px; padding: 3px 8px; text-align: right;
  font-family: var(--mono); font-size: 0.86rem; font-weight: 600; white-space: nowrap;
  background: var(--readout); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.08);
}
/* Results panel gets .mode-basic too: swap the last row between modes */
.results-panel:not(.mode-basic) [data-basic] { display: none; }

/* ---------- Notes (alarm banner style) ---------- */
.notes { margin-top: 10px; display: grid; gap: 6px; }
.notes:empty { display: none; }
.note {
  font-size: 0.8rem; line-height: 1.4;
  padding: 6px 10px 6px 32px; position: relative;
  border-radius: var(--radius);
  border: 1px solid #a88600; border-left: 6px solid var(--warn);
  background: var(--warn-bg); color: var(--warn-text);
}
.note::before {
  content: "!"; position: absolute; left: 8px; top: 6px;
  width: 0; height: 0; border-left: 8px solid transparent; border-right: 8px solid transparent; border-bottom: 14px solid #1a1f24;
  font-size: 0.6rem; font-weight: 800; color: var(--warn); line-height: 20px; text-indent: -2px;
}
.note.error { border-color: #8f1d1d; border-left-color: var(--alarm); background: var(--alarm-bg); color: var(--alarm-text); }
.note.error::before { border: 0; width: 14px; height: 14px; background: var(--alarm); content: "×"; color: #fff; display: grid; place-items: center; line-height: 1; text-indent: 0; font-size: 0.8rem; }

/* ---------- Formula table ---------- */
.formulas { margin-top: 12px; }
.table-wrap { overflow-x: auto; }
.formula-table { width: 100%; border-collapse: collapse; font-size: 0.82rem; }
.formula-table th, .formula-table td { padding: 6px 12px; text-align: left; border-bottom: 1px solid var(--line); vertical-align: top; }
.formula-table tr:last-child th, .formula-table tr:last-child td { border-bottom: 0; }
.formula-table thead th {
  font-size: 0.68rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--text-2); background: var(--panel-2);
}
.formula-table tbody tr:nth-child(even) { background: rgba(255, 255, 255, 0.35); }
.formula-table tbody th { font-weight: 600; color: var(--text-2); white-space: nowrap; }
.formula-table .f, .formula-table .sub { font-family: var(--mono); font-size: 0.78rem; }
.formula-table .sub { color: var(--muted); }
.formula-table .num, .formula-table .res { text-align: right; white-space: nowrap; font-weight: 700; font-family: var(--mono); }

@media (max-width: 719px) {
  .formula-table thead { display: none; }
  .formula-table tr { display: grid; grid-template-columns: 1fr auto; gap: 2px 12px; padding: 8px 12px; border-bottom: 1px solid var(--line); }
  .formula-table tr:last-child { border-bottom: 0; }
  .formula-table th, .formula-table td { padding: 0; border: 0; }
  .formula-table .f, .formula-table .sub { grid-column: 1 / -1; white-space: normal; overflow-wrap: anywhere; }
  .formula-table tbody th { grid-row: 1; }
  .formula-table .res { grid-row: 1; grid-column: 2; }
}

/* ---------- Explanation ---------- */
.info-grid { display: grid; gap: 12px; margin-top: 12px; grid-template-columns: minmax(0, 1fr); }
@media (min-width: 900px) { .info-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.prose p { margin: 0 0 10px; color: var(--text-2); font-size: 0.86rem; }
.prose .muted { color: var(--muted); font-size: 0.8rem; margin-bottom: 0; }
.eq-block {
  font-family: var(--mono); font-size: 0.88rem !important; color: var(--text) !important;
  background: var(--readout); border: 1px solid var(--line-strong); border-left: 4px solid var(--title);
  border-radius: var(--radius); padding: 7px 12px;
}
.glossary { margin: 0; display: grid; grid-template-columns: minmax(110px, 34%) 1fr; gap: 7px 14px; font-size: 0.82rem; }
.glossary dt { font-weight: 700; color: var(--text); }
.glossary dd { margin: 0; color: var(--text-2); }
@media (max-width: 480px) {
  .glossary { grid-template-columns: 1fr; gap: 2px; }
  .glossary dd { margin-bottom: 8px; }
}

/* ---------- Contact banner ---------- */
.contact {
  margin-top: 12px; padding: 14px 16px;
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px;
  background: var(--title); border-color: var(--chrome); color: #fff;
}
.contact h2 { font-size: 1rem; }
.contact p { margin: 3px 0 0; color: #c9d0d7; font-size: 0.84rem; }
.btn {
  display: inline-block; padding: 8px 18px; border-radius: var(--radius);
  background: var(--select); color: #fff; text-decoration: none; font-weight: 700; font-size: 0.82rem;
  letter-spacing: 0.05em; text-transform: uppercase; border: 1px solid #1f4d7d;
}
.btn:hover { background: #255a91; }

/* ---------- Home page calculator list ---------- */
.calc-list {
  list-style: none; padding: 0; margin: 0;
  display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}
.calc-card {
  display: flex; flex-direction: column; gap: 6px; height: 100%;
  padding: 14px 16px; text-decoration: none; color: inherit;
  border-top: 4px solid var(--title);
}
.calc-card:hover { border-color: var(--select); }
.calc-card .tag { font-size: 0.68rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.calc-card h2 { font-size: 1rem; }
.calc-card p { margin: 0; color: var(--text-2); font-size: 0.84rem; flex: 1; }
.calc-card .go { font-size: 0.8rem; font-weight: 700; color: var(--select); }

/* Small phones: drop the long unit hint from the calculation-steps title bar */
@media (max-width: 520px) { .formulas .panel-meta { display: none; } }
.assumptions-warn { margin: 0 0 8px; font-size: 0.78rem; color: var(--muted); }

/* =====================================================================
   Header theme toggle + DARK THEME
   ---------------------------------------------------------------------
   <html data-theme="dark"> is set by the inline script in each page's
   <head> and by js/theme.js. Only tokens change, so every component
   (including the SVG drawing) follows automatically.
   ===================================================================== */
.header-right { display: flex; align-items: center; gap: 10px; }
.theme-toggle {
  display: inline-grid; grid-auto-flow: column; grid-auto-columns: 1fr; gap: 2px; padding: 2px;
  background: #15191d; border: 1px solid #3a424b; border-radius: var(--radius);
}
.theme-toggle button {
  padding: 3px 10px; border: 0; border-radius: 2px; background: transparent; cursor: pointer;
  font: inherit; font-size: 0.7rem; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase;
  color: #aeb6be;
}
.theme-toggle button:hover { color: #fff; }
.theme-toggle button[aria-pressed="true"] { background: #4b555f; color: #fff; }
.theme-toggle button:focus-visible { outline: 2px solid #fff; outline-offset: -2px; }
@media (max-width: 420px) {
  .site-nav { display: none; }
}

:root { color-scheme: light; }

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #16191d;
  --panel: #22272d;
  --panel-2: #2b3138;
  --title: #353d46;
  --chrome: #0d1013;
  --canvas: #1b1f24;
  --field: #121519;
  --readout: #181c20;
  --line: #363e47;
  --line-strong: #4a535d;
  --text: #e4e8ec;
  --text-2: #c0c7ce;
  --muted: #8d97a1;
  --select: #3d7fc4;
  --select-soft: rgba(61, 127, 196, 0.32);
  --warn-bg: #3a3112;
  --warn-text: #f4dc84;
  --alarm-bg: #3b1d1d;
  --alarm-text: #f5b4b4;
  --svg-frame: #6f7984;
  --svg-belt: #cdd3d9;
  --svg-pulley: #535c66;
  --svg-pulley-hub: #e4e8ec;
  --svg-box: #a8956d;
  --svg-box-edge: #786848;
  --svg-motor: #627789;
  --svg-gearbox: #7c92a8;
  --svg-chain: #c77b5e;
  --svg-arrow: #5c9de2;
  --svg-force: #e86a6a;
  --svg-floor: #4f5862;
}
:root[data-theme="dark"] .site-header { border-bottom-color: #2a3139; }
:root[data-theme="dark"] .kpi.primary { background: #0c0f12; border-color: #000; }
:root[data-theme="dark"] .note { border-color: #6d5a10; border-left-color: var(--warn); }
:root[data-theme="dark"] .note.error { border-color: #6b2323; border-left-color: var(--alarm); }
:root[data-theme="dark"] .formula-table tbody tr:nth-child(even) { background: rgba(255, 255, 255, 0.03); }
:root[data-theme="dark"] .contact { background: var(--panel-2); border-color: var(--line-strong); }
/* Dropdown arrows need a light fill on dark fields */
:root[data-theme="dark"] .param-select,
:root[data-theme="dark"] .input-unit .unit-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='8' height='5'%3E%3Cpath d='M0 0l4 5 4-5z' fill='%23c0c7ce'/%3E%3C/svg%3E");
}