lab.css

/* ============================================================
   Euler Laboratory — shared instrument-panel skin
   Cosmetic only. Linked from index.html and index2d.html.
   All colours are :root variables so the theme is easy to tweak.
   Physics "screens" (tube / nozzle / heatmap / plots) keep their
   own cream palette in the JS and are intentionally NOT themed here.
   ============================================================ */

:root {
  /* surfaces (dark chassis) */
  --bg:         #14161a;   /* page background            */
  --surface:    #1b1e24;   /* grouped control cards / nav */
  --surface-2:  #21252c;   /* raised chips               */
  --field:      #23272f;   /* inputs, selects            */
  --elevated:   #0e1013;   /* control rail + plot backdrop (darkest) */

  /* ink */
  --ink:        #e7e9ec;   /* primary text               */
  --muted:      #98a0ab;   /* secondary / labels         */
  --faint:      #333a44;   /* card & input borders       */
  --line:       #2a3038;   /* hairline separators        */

  /* accents (harmonise with the cream→gold→rust colormap) */
  --accent:     #e2724b;   /* rust primary               */
  --accent-hi:  #ef8763;   /* rust hover                 */
  --accent-ink: #17110d;   /* text on accent             */
  --accent-2:   #d7a33c;   /* amber — live / running     */
  --danger:     #e2724b;
  --danger-bg:  #2b1a15;

  /* system font stacks — no downloads */
  --font-mono: ui-monospace, 'SF Mono', SFMono-Regular, Menlo, Consolas, 'Liberation Mono', monospace;
  --font-display: ui-serif, 'Iowan Old Style', 'Palatino Linotype', Palatino, Georgia, 'Times New Roman', serif;

  /* spacing / shape scale */
  --r-sm: 6px;
  --r-md: 9px;
  --r-lg: 12px;
  --shadow: 0 1px 0 rgba(255,255,255,0.03), 0 8px 24px rgba(0,0,0,0.35);
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
}
body {
  font-family: var(--font-mono);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: rgba(226,114,75,0.30); }

/* faint instrument grain over the dark chassis */
.grain {
  background-image: radial-gradient(rgba(255,255,255,0.028) 1px, transparent 1px);
  background-size: 3px 3px;
}

.smallcaps { font-variant: small-caps; letter-spacing: 0.12em; }

/* ---------------- Buttons ---------------- */
.btn {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 8px 13px;
  border: 1px solid var(--faint);
  border-radius: var(--r-sm);
  background: var(--field);
  color: var(--ink);
  cursor: pointer;
  transition: background 130ms ease, color 130ms ease,
              border-color 130ms ease, transform 60ms ease, box-shadow 130ms ease;
}
.btn:hover:not(:disabled) {
  background: var(--surface-2);
  border-color: #4a525e;
  color: #fff;
}
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(226,114,75,0.30);
}
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
  box-shadow: 0 2px 10px rgba(226,114,75,0.28);
}
.btn-primary:hover:not(:disabled) {
  background: var(--accent-hi);
  border-color: var(--accent-hi);
  color: var(--accent-ink);
}

/* ---------------- Selects ---------------- */
select {
  font-family: var(--font-mono);
  font-size: 13px;
  padding: 6px 26px 6px 9px;
  background-color: var(--field);
  color: var(--ink);
  border: 1px solid var(--faint);
  border-radius: var(--r-sm);
  outline: none;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='7' viewBox='0 0 10 7'><path d='M1 1l4 4 4-4' fill='none' stroke='%2398a0ab' stroke-width='1.4' stroke-linecap='round'/></svg>");
  background-repeat: no-repeat;
  background-position: right 9px center;
  transition: border-color 130ms ease, box-shadow 130ms ease;
}
select:hover { border-color: #4a525e; }
select:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(226,114,75,0.28);
}
select option { background: var(--field); color: var(--ink); }

/* ---------------- Number inputs ---------------- */
input[type=number] {
  transition: border-color 130ms ease, box-shadow 130ms ease, background 130ms ease;
}
input[type=number]:hover { border-color: #4a525e !important; }
input[type=number]:focus-visible {
  border-color: var(--accent) !important;
  box-shadow: 0 0 0 3px rgba(226,114,75,0.26);
}
input[type=number]::-webkit-inner-spin-button,
input[type=number]::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }
input[type=number] { -moz-appearance: textfield; }

/* ---------------- Checkboxes ---------------- */
input[type=checkbox] {
  accent-color: var(--accent);
  width: 14px; height: 14px;
  cursor: pointer;
}

/* ---------------- Range sliders (styled for completeness) ---------------- */
input[type=range] {
  -webkit-appearance: none;
  appearance: none;
  height: 4px;
  border-radius: 3px;
  background: var(--line);
  outline: none;
  cursor: pointer;
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 15px; height: 15px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  box-shadow: 0 1px 4px rgba(0,0,0,0.5);
}
input[type=range]::-moz-range-thumb {
  width: 15px; height: 15px;
  border: 2px solid var(--bg);
  border-radius: 50%;
  background: var(--accent);
}

/* ---------------- Grouped control cards (fieldsets) ---------------- */
fieldset {
  background: var(--surface);
  border-radius: var(--r-lg) !important;
  box-shadow: var(--shadow);
}
legend { color: var(--muted); }

/* ---------------- Tab links ---------------- */
a.tablink {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px dashed var(--faint);
  transition: color 130ms ease, border-color 130ms ease;
}
a.tablink:hover { color: var(--accent); border-bottom-color: var(--accent); }

/* ---------------- Disclosure ---------------- */
details summary { color: var(--muted); }
details summary:hover { color: var(--ink); }

/* ---------------- Scrollbar ---------------- */
* { scrollbar-color: var(--faint) var(--bg); }
::-webkit-scrollbar { width: 12px; height: 12px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb {
  background: var(--faint);
  border-radius: 8px;
  border: 3px solid var(--bg);
}
::-webkit-scrollbar-thumb:hover { background: #454d59; }