:root {
  /* Light theme palette (GitHub-like) */
  --bg: #ffffff;
  --panel: #ffffff;
  --fg: #24292f;
  --muted: #57606a;
  --accent: #0969da;  /* blue for v(t) */

  --green: #1a7f37;   /* pre-reset markers */
  --yellow: #9a6700;  /* bias pulse */
  --red: #d1242f;     /* out spike */
  --orange: #bc4c00;  /* B */
  --cyan: #1b7c83;    /* A */
  --purple: #8250df;  /* threshold */

  --border: #d0d7de;
  --panel-soft: #f6f8fa; /* subtle fills (chips, inputs) */
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--fg);
  background: var(--bg);
}

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px;
}

header h1 { margin: 0 0 8px; font-size: 28px; color: var(--fg); }
header p { margin: 0 0 16px; color: var(--muted); }

.controls, .plot-section, footer {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 16px;
}

.control-row {
  display: flex;
  gap: 16px;
  align-items: center;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.control-row label { display: inline-flex; align-items: center; gap: 8px; color: var(--fg); }
.control-row select, .control-row button {
  background: var(--panel-soft);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
}

button { cursor: pointer; }
button:hover { border-color: var(--accent); }

fieldset {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
}
legend { color: var(--muted); padding: 0 6px; }

.toggle input { transform: scale(1.1); }

.readout {
  gap: 32px;
  font-size: 16px;
  color: var(--fg);
}

.plot-section {
  text-align: center;
  position: relative; /* anchor tooltip */
}

canvas {
  display: block;
  width: 100%;
  height: auto;
  background: #ffffff;     /* white canvas */
  border: 1px dashed var(--border);
  border-radius: 8px;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
  justify-content: center;
  margin-top: 10px;
}

.chip {
  display: inline-block;
  padding: 4px 8px;
  border-radius: 999px;
  font-size: 12px;
  border: 1px solid var(--border);
  background: var(--panel-soft);
  color: var(--muted);
}
.chip-v { color: var(--accent); }
.chip-th { color: var(--purple); }
.chip-A { color: var(--cyan); }
.chip-B { color: var(--orange); }
.chip-bias { color: var(--yellow); }
.chip-out { color: var(--red); }

/* Tooltip styling (light) */
.plot-tooltip {
  position: absolute;
  background: #ffffff;
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 8px;
  font-size: 12px;
  pointer-events: none;
  white-space: nowrap;
  box-shadow: 0 8px 24px rgba(0,0,0,0.12);
  display: none;
  z-index: 2;
}
.plot-tooltip .row {
  display: flex;
  align-items: center;
  gap: 6px;
  line-height: 1.25;
}
.plot-tooltip .swatch {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  display: inline-block;
}

footer p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}