* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* --- Theme variables --- */
:root {
  --bg-body: #0f0f23;
  --bg-sidebar: #1a1a2e;
  --bg-input: #2a2a4a;
  --bg-input-border: #3a3a5a;
  --bg-stats: #22223a;
  --bg-btn-secondary: #2a2a4a;
  --bg-btn-secondary-hover: #3a3a5a;
  --bg-speed-preset: #2a2a4a;
  --bg-speed-preset-hover: #3a3a5a;
  --border-sidebar: #2a2a4a;
  --border-separator: #2a2a4a;
  --text-primary: #e0e0e0;
  --text-heading: #7eb8da;
  --text-label: #99aabb;
  --text-muted: #8899aa;
  --text-help: #667788;
  --text-value: #7eb8da;
  --text-fit: #5dbe8a;
  --text-btn-secondary: #aabbcc;
  --accent: #4183d7;
  --accent-hover: #5a9ae6;
  --accent-active: #e67e22;
  --accent-green: #2d6a4f;
  --accent-green-hover: #3a8a6a;
  --slider-track: #2a2a4a;
}

body.light {
  --bg-body: #f0f2f5;
  --bg-sidebar: #ffffff;
  --bg-input: #e8ecf0;
  --bg-input-border: #ccd3da;
  --bg-stats: #f0f2f5;
  --bg-btn-secondary: #e0e4e8;
  --bg-btn-secondary-hover: #d0d4d8;
  --bg-speed-preset: #e0e4e8;
  --bg-speed-preset-hover: #d0d4d8;
  --border-sidebar: #d0d4d8;
  --border-separator: #d8dce0;
  --text-primary: #1a1a2e;
  --text-heading: #2a6496;
  --text-label: #556677;
  --text-muted: #667788;
  --text-help: #8899aa;
  --text-value: #2a6496;
  --text-fit: #2d8a5e;
  --text-btn-secondary: #445566;
  --accent: #3572b0;
  --accent-hover: #4183d7;
  --accent-active: #d35400;
  --accent-green: #2d8a5e;
  --accent-green-hover: #38a06d;
  --slider-track: #d0d4d8;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-body);
  color: var(--text-primary);
  height: 100vh;
  overflow: hidden;
}

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

/* --- Sidebar --- */
.sidebar {
  width: 260px;
  min-width: 260px;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-sidebar);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  overflow-y: auto;
}

.sidebar h1 {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-heading);
  margin-bottom: 4px;
}

.sidebar h1 small {
  display: block;
  font-size: 11px;
  font-weight: 400;
  color: var(--text-muted);
  margin-top: 2px;
}

/* --- Header row --- */
.header-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.btn-info {
  background: none;
  color: var(--text-heading);
  font-size: 22px;
  padding: 0 4px;
  line-height: 1;
  opacity: 0.7;
  flex-shrink: 0;
}

.btn-info:hover {
  opacity: 1;
}

/* --- Bias labels --- */
.bias-label-row {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-muted);
  padding: 0 2px;
}


/* --- Control groups --- */
.control-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.control-group label {
  font-size: 12px;
  font-weight: 500;
  color: var(--text-label);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.control-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.control-row input[type="range"] {
  flex: 1;
}

.control-row .value-display {
  min-width: 36px;
  text-align: right;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-value);
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  background: var(--slider-track);
  border-radius: 3px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
  width: 16px;
  height: 16px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
  border: none;
}

input[type="number"] {
  width: 100%;
  padding: 6px 8px;
  background: var(--bg-input);
  border: 1px solid var(--bg-input-border);
  border-radius: 4px;
  color: var(--text-primary);
  font-size: 13px;
  outline: none;
}

input[type="number"]:focus {
  border-color: var(--accent);
}

/* --- Buttons --- */
.button-row {
  display: flex;
  gap: 8px;
}

button {
  padding: 8px 16px;
  border: none;
  border-radius: 4px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  flex: 1;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-primary.active {
  background: var(--accent-active);
}

.btn-secondary {
  background: var(--bg-btn-secondary);
  color: var(--text-btn-secondary);
  flex: 1;
}

.btn-secondary:hover {
  background: var(--bg-btn-secondary-hover);
}

.btn-accent {
  background: var(--accent-green);
  color: #e0e0e0;
  flex: 1;
}

.btn-accent:hover {
  background: var(--accent-green-hover);
}

.toggle-inline {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  color: var(--text-muted);
  cursor: pointer;
  margin-top: 2px;
}

.toggle-inline input[type="checkbox"] {
  accent-color: var(--accent);
}

/* Step buttons (+/-) */
.step-btn {
  padding: 0 6px;
  font-size: 14px;
  background: var(--bg-btn-secondary);
  color: var(--text-muted);
  border-radius: 3px;
  line-height: 1.4;
  flex-shrink: 0;
}

.step-btn:hover {
  color: var(--text-primary);
  background: var(--bg-btn-secondary-hover);
}

/* Speed presets */
.speed-presets {
  display: flex;
  gap: 4px;
}

.speed-preset {
  padding: 4px 8px;
  font-size: 11px;
  background: var(--bg-speed-preset);
  color: var(--text-muted);
  border-radius: 3px;
}

.speed-preset:hover {
  background: var(--bg-speed-preset-hover);
  color: var(--text-btn-secondary);
}

/* --- Toggles --- */
.toggle-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toggle-group label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-label);
  cursor: pointer;
}

.toggle-group input[type="checkbox"] {
  accent-color: var(--accent);
}

/* --- Stats overlay (top-right of canvas, below theme/fullscreen buttons) --- */
.stats-overlay {
  position: absolute;
  top: 40px;
  right: 10px;
  background: var(--bg-sidebar);
  border-radius: 6px;
  padding: 8px 12px;
  z-index: 10;
  opacity: 0.85;
  pointer-events: none;
}

.stat-row {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  padding: 2px 0;
  gap: 12px;
}

.stat-row .stat-label {
  color: var(--text-muted);
}

.stat-row .stat-value {
  color: var(--text-value);
  font-weight: 600;
  font-family: monospace;
}

.stat-row .stat-value.fit-label {
  color: var(--text-fit);
}

/* --- Separator --- */
.separator {
  border: none;
  border-top: 1px solid var(--border-separator);
  margin: 2px 0;
}

/* --- Info overlay --- */
.overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(0, 0, 0, 0.6);
  justify-content: center;
  align-items: center;
  padding: 20px;
}

.overlay.visible {
  display: flex;
}

.overlay-content {
  background: var(--bg-sidebar);
  color: var(--text-primary);
  border-radius: 12px;
  padding: 32px;
  max-width: 640px;
  max-height: 85vh;
  overflow-y: auto;
  position: relative;
  line-height: 1.6;
}

.overlay-content h2 {
  font-size: 22px;
  color: var(--text-heading);
  margin-bottom: 16px;
}

.overlay-content h3 {
  font-size: 15px;
  color: var(--text-heading);
  margin-top: 20px;
  margin-bottom: 8px;
}

.overlay-content p {
  font-size: 14px;
  margin-bottom: 10px;
  color: var(--text-primary);
}

.overlay-content ul {
  font-size: 14px;
  margin: 8px 0 10px 20px;
  color: var(--text-primary);
}

.overlay-content li {
  margin-bottom: 6px;
}

.overlay-content .formula {
  text-align: center;
  font-family: monospace;
  font-size: 15px;
  color: var(--text-value);
  padding: 8px;
  background: var(--bg-stats);
  border-radius: 6px;
}

.overlay-close {
  position: absolute;
  top: 12px;
  right: 16px;
  font-size: 24px;
  background: none;
  color: var(--text-muted);
  padding: 4px 8px;
  cursor: pointer;
}

.overlay-close:hover {
  color: var(--text-primary);
}

/* --- Canvas area --- */
.canvas-container {
  flex: 1;
  position: relative;
  min-width: 0;
}

.canvas-container canvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* --- Progress bar --- */
.progress-bar {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 10;
  background: transparent;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.2s ease;
  border-radius: 0 2px 2px 0;
}

/* --- Shortcut toast --- */
.shortcut-toast {
  position: absolute;
  bottom: 16px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(0, 0, 0, 0.7);
  color: #ddd;
  font-size: 12px;
  padding: 8px 16px;
  border-radius: 6px;
  z-index: 10;
  opacity: 1;
  transition: opacity 1s ease;
  pointer-events: none;
  white-space: nowrap;
}

.shortcut-toast.hidden {
  opacity: 0;
}

body.light .shortcut-toast {
  background: rgba(0, 0, 0, 0.6);
  color: #eee;
}

/* --- Canvas overlay buttons --- */
.canvas-btn {
  position: absolute;
  top: 10px;
  background: var(--bg-btn-secondary);
  color: var(--text-muted);
  font-size: 18px;
  padding: 4px 10px;
  border-radius: 4px;
  opacity: 0.5;
  z-index: 10;
}

.canvas-btn:hover {
  opacity: 1;
}

.shortcuts-wrapper {
  position: absolute;
  top: 10px;
  right: 90px;
  z-index: 10;
}

.shortcuts-btn {
  position: static;
  font-size: 14px;
  font-weight: bold;
  padding: 4px 11px;
}

.shortcuts-panel {
  display: none;
  position: absolute;
  top: 32px;
  right: 0;
  background: var(--bg-sidebar);
  border-radius: 6px;
  padding: 8px 12px;
  font-size: 11px;
  color: var(--text-primary);
  white-space: nowrap;
  line-height: 1.8;
  opacity: 0.9;
}

.shortcuts-wrapper:hover .shortcuts-panel,
.shortcuts-panel.visible {
  display: block;
}

.shortcuts-panel b {
  color: var(--text-value);
  min-width: 36px;
  display: inline-block;
}

.theme-btn {
  right: 50px;
}

.theme-btn.active {
  color: var(--text-heading);
  opacity: 0.8;
}

.fullscreen-btn {
  right: 10px;
  background: var(--bg-btn-secondary);
  color: var(--text-muted);
  font-size: 18px;
  padding: 4px 10px;
  border-radius: 4px;
  opacity: 0.5;
  z-index: 10;
}

.fullscreen-btn:hover {
  opacity: 1;
}

/* --- Fullscreen mode --- */
.app.fullscreen .sidebar {
  display: none;
}

.app.fullscreen .canvas-container {
  width: 100%;
}

.app.fullscreen .fullscreen-btn {
  opacity: 0.7;
}

/* --- Help text --- */
.help-text {
  font-size: 10px;
  color: var(--text-help);
  line-height: 1.4;
}

/* --- Responsive --- */
@media (max-width: 700px) {
  .app {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    min-width: unset;
    max-height: 40vh;
    border-right: none;
    border-bottom: 1px solid var(--border-sidebar);
    padding: 10px;
    gap: 8px;
  }

  /* Two-column layout when sidebar is horizontal on narrow screens */
  .sidebar > .control-group,
  .sidebar > .toggle-group,
  .sidebar > .stats-panel,
  .sidebar > .button-row,
  .sidebar > .help-text,
  .sidebar > .separator {
    display: contents;
  }

  .sidebar {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px 12px;
  }

  .sidebar h1 {
    grid-column: 1 / -1;
  }

  .sidebar hr.separator {
    grid-column: 1 / -1;
    display: block;
  }

  .sidebar .button-row {
    grid-column: 1 / -1;
    display: flex;
  }

  .sidebar .help-text {
    grid-column: 1 / -1;
    display: block;
  }
}