:root {
  --bg: #f7f8fa;
  --panel-bg: #ffffff;
  --border: #e1e4e8;
  --text: #1c2126;
  --text-dim: #5b6570;
  --accent: #2563eb;
  --accent-contrast: #ffffff;
  --code-bg: #f2f4f7;
  --ok: #1a8f5e;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06);
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Hiragino Sans, "Noto Sans JP", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171c;
    --panel-bg: #1b1f26;
    --border: #2b313a;
    --text: #e6e9ee;
    --text-dim: #8b95a1;
    --accent: #5b8dfa;
    --accent-contrast: #0b1220;
    --code-bg: #10141a;
    --ok: #4ade9d;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body { background: var(--bg); color: var(--text); font-family: var(--sans); font-size: 14px; }

.app { display: flex; height: 100vh; min-height: 100vh; }

.sidebar {
  width: 260px;
  flex: none;
  border-right: 1px solid var(--border);
  background: var(--panel-bg);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.brand { padding: 18px 16px 14px; border-bottom: 1px solid var(--border); }
.brand-title { font-weight: 700; font-size: 16px; }
.brand-badge {
  font-size: 10px;
  font-weight: 700;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: 2px 6px;
  border-radius: 4px;
  vertical-align: middle;
  margin-left: 6px;
}
.brand-sub { margin-top: 6px; font-size: 11.5px; color: var(--text-dim); line-height: 1.5; }
.brand-support-link {
  display: inline-block;
  margin-top: 6px;
  font-size: 11.5px;
  color: var(--accent);
  text-decoration: none;
}
.brand-support-link:hover { text-decoration: underline; }

.figure-list { padding: 8px; }
.chapter-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  padding: 14px 8px 4px;
}
.figure-item {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  border-radius: 6px;
  padding: 7px 10px;
  color: var(--text);
  font-size: 13px;
  cursor: pointer;
}
.figure-item:hover { background: var(--code-bg); }
.figure-item.active { background: var(--accent); color: var(--accent-contrast); font-weight: 600; }

.panel { flex: 1; display: flex; flex-direction: column; min-width: 0; overflow-y: auto; }

.panel-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 24px 12px;
  border-bottom: 1px solid var(--border);
}
.title-block h1 { margin: 0; font-size: 18px; }
.fig-note { margin: 4px 0 0; font-size: 12px; color: var(--text-dim); line-height: 1.5; }

.controls { display: flex; align-items: center; gap: 12px; flex: none; }
.status { font-size: 12.5px; color: var(--text-dim); white-space: nowrap; }
.status.ok { color: var(--ok); }
.status.error { color: #d3402f; }

.run-btn {
  background: var(--accent);
  color: var(--accent-contrast);
  border: none;
  border-radius: 6px;
  padding: 8px 18px;
  font-size: 13.5px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: var(--shadow);
}
.run-btn:disabled { opacity: 0.45; cursor: default; }
.run-btn:not(:disabled):hover { filter: brightness(1.08); }

.params-panel {
  display: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--code-bg);
  padding: 14px 16px;
  margin: 20px 24px 0;
}
.params-title { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-dim); margin-bottom: 10px; }
.params-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 10px 16px; }
.params-grid + .params-grid { margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border); }
.params-field { display: flex; flex-direction: column; gap: 6px; font-size: 12px; color: var(--text-dim); }
.params-field-header { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.params-label { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.params-value {
  font-family: "SFMono-Regular", Consolas, Menlo, monospace;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--text);
  flex: none;
}

.params-field input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 4px;
  border-radius: 2px;
  background: var(--border);
  outline: none;
  cursor: pointer;
}
.params-field input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  box-shadow: 0 0 0 1px var(--accent);
  cursor: pointer;
}
.params-field input[type="range"]::-moz-range-thumb {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  box-shadow: 0 0 0 1px var(--accent);
  cursor: pointer;
}

/* Dual-handle range ("range2"): two native <input type=range> stacked on
   the same track via absolute positioning -- each track/background is made
   transparent (pointer-events:none) so only the two thumbs are interactive,
   with a separate .range2-rail/.range2-fill pair drawn behind them for the
   single visible track + highlighted-span look. */
.params-range2-track { position: relative; height: 20px; }
.params-range2-track .range2-rail {
  position: absolute;
  left: 0;
  right: 0;
  top: 8px;
  height: 4px;
  border-radius: 2px;
  background: var(--border);
}
.params-range2-track .range2-fill {
  position: absolute;
  top: 8px;
  height: 4px;
  border-radius: 2px;
  background: var(--accent);
  opacity: 0.55;
}
.params-range2-track input[type="range"] {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 20px;
  margin: 0;
  background: transparent;
  pointer-events: none;
  -webkit-appearance: none;
  appearance: none;
}
.params-range2-track input[type="range"]::-webkit-slider-runnable-track {
  background: transparent;
}
.params-range2-track input[type="range"]::-moz-range-track {
  background: transparent;
}
.params-range2-track input[type="range"]::-webkit-slider-thumb {
  pointer-events: auto;
  -webkit-appearance: none;
  appearance: none;
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  box-shadow: 0 0 0 1px var(--accent);
  cursor: pointer;
}
.params-range2-track input[type="range"]::-moz-range-thumb {
  pointer-events: auto;
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  box-shadow: 0 0 0 1px var(--accent);
  cursor: pointer;
}

.params-text-input {
  font-family: "SFMono-Regular", Consolas, Menlo, monospace;
  font-size: 12.5px;
  color: var(--text);
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
  width: 100%;
  box-sizing: border-box;
  resize: vertical;
}

.params-select {
  font-size: 12.5px;
  color: var(--text);
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
  width: 100%;
  box-sizing: border-box;
}

.output-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 20px;
  padding: 20px 24px;
}

.output-card { display: flex; flex-direction: column; gap: 6px; min-width: 0; }
.output-card-title { font-size: 12.5px; color: var(--text-dim); }
.output-card-body { overflow: auto; max-width: 100%; }
/* NOTE: no `.chart-wrap { max-width: 100% }` here -- that would cap the
   wrapper div's measured width against its container before plot.js's
   finalizeResponsiveLayout() gets to measure its true natural size, which
   defeats the transform-based scaling (the wrapper looks pre-shrunk while
   the fixed-size <canvas> inside it doesn't shrink and overflows anyway). */

.hint { color: var(--text-dim); font-size: 12.5px; line-height: 1.6; margin: 8px 24px; }

.notes { border-top: 1px solid var(--border); padding: 10px 24px; margin-top: auto; }
.notes p { margin: 0; font-size: 11.5px; color: var(--text-dim); line-height: 1.6; }
.notes a { color: var(--accent); }

/* ---------- Chart widgets ---------- */

.chart-wrap {
  position: relative;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #ffffff;
  padding: 10px 10px 34px 58px;
  box-shadow: var(--shadow);
  display: inline-block;
}

.chart-xlabel {
  position: absolute;
  left: 50%;
  bottom: 8px;
  transform: translateX(-50%);
  font-size: 13px;
  color: #374151;
}
.chart-3d-zlabel { display: none; } /* superseded by .chart-3d-axis-label, dynamically positioned */

.chart-3d-axis-label {
  position: absolute;
  transform: translate(-50%, -50%);
  font-size: 13px;
  color: #374151;
  white-space: nowrap;
}

.chart-ylabel {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%) rotate(-90deg);
  transform-origin: center;
  font-size: 13px;
  color: #374151;
}

.chart-legend {
  position: absolute;
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid #d8dbe0;
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 12px;
  color: #1c2126;
}
.chart-legend.loc-ur { top: 14px; right: 16px; }
.chart-legend.loc-ul { top: 14px; left: 66px; }
.chart-legend-row { display: flex; align-items: center; gap: 6px; padding: 2px 0; white-space: nowrap; }
.chart-legend-swatch { display: inline-block; width: 16px; height: 3px; flex: none; }
.chart-legend-swatch:has(+ .chart-legend-label) { }

@media (max-width: 820px) {
  .app { flex-direction: column; }
  .sidebar { width: 100%; height: 34vh; border-right: none; border-bottom: 1px solid var(--border); }
  .panel { height: 66vh; }
  .output-grid { grid-template-columns: 1fr; padding: 14px; }
  .params-panel { margin: 14px; }
}