:root {
  color-scheme: dark;
  --bg: #1a1a1a;
  --fg: #e6e6e6;
  --muted: #888;
  --border: #333;
  --panel: #222;
  --accent: #00e6ff;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  background: var(--bg);
  color: var(--fg);
}

header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
}

header h1 {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 600;
}

.subtitle {
  margin: 0.25rem 0 0;
  color: var(--muted);
  font-size: 0.875rem;
}

.muted {
  color: var(--muted);
}

main {
  display: grid;
  grid-template-columns: 280px 1fr 280px;
  gap: 1rem;
  padding: 1rem;
  align-items: start;
}

body:not(.has-image) main {
  grid-template-columns: 280px 1fr;
}

body:not(.has-image) #tracks {
  display: none;
}

aside,
section {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
}

aside h2 {
  margin: 0 0 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

#canvas-mount {
  padding: 0.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  overflow: auto;
}

body:not(.has-image) #canvas-mount {
  cursor: pointer;
}

body:not(.has-image) #canvas-mount canvas {
  outline: 2px dashed var(--accent);
  outline-offset: 4px;
}

body:not(.has-image) #canvas-mount:hover canvas {
  outline-color: var(--fg);
}

#canvas-mount > .transport {
  width: min(360px, 100%);
  margin-top: 0;
}

.replace-image {
  display: none;
  background: none;
  border: none;
  color: var(--muted);
  font-size: 0.75rem;
  text-decoration: underline;
  cursor: pointer;
  padding: 0;
}

.replace-image:hover {
  color: var(--fg);
}

body.has-image .replace-image {
  display: inline-block;
}

#canvas-mount canvas {
  display: block;
  margin: 0 auto;
  max-width: 100% !important;
  max-height: 80vh !important;
  width: auto !important;
  height: auto !important;
}

#file-input-mount {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

/* Transport buttons --------------------------------------------------------- */
.transport {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.75rem;
}

.transport button {
  flex: 1;
  padding: 0.4rem 0.5rem;
  background: #2d2d2d;
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 0.8125rem;
  cursor: pointer;
}

.transport button:hover {
  background: #3a3a3a;
  border-color: #444;
}

.transport button:active {
  background: #222;
}

/* Sliders ------------------------------------------------------------------- */
.slider-row {
  display: grid;
  grid-template-columns: 1fr;
  margin-top: 0.5rem;
  font-size: 0.75rem;
  color: var(--muted);
}

.slider-row .label {
  display: block;
}

.slider-row input[type="range"] {
  display: block;
  width: 100%;
  margin-top: 0.2rem;
}

.slider-row .value {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  color: var(--fg);
  font-size: 0.7rem;
  text-align: right;
  margin-top: -0.9rem;
  pointer-events: none;
}

/* Toggle (checkbox) --------------------------------------------------------- */
.toggle {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 0.75rem;
  font-size: 0.8125rem;
  color: var(--fg);
  cursor: pointer;
}

.toggle input {
  margin: 0;
  cursor: pointer;
}

.toggle label {
  cursor: pointer;
}

/* Detection sub-panel ------------------------------------------------------- */
.subpanel {
  margin-top: 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
}

.subpanel-title {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

/* Stats --------------------------------------------------------------------- */
#stats {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.8125rem;
  color: var(--muted);
  margin-top: 0.75rem;
  word-break: break-word;
}

/* Tracks panel -------------------------------------------------------------- */
#tracks {
  max-height: calc(100vh - 4rem);
  overflow-y: auto;
}

#tracks-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

#tracks-count {
  font-size: 0.7rem;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}

#tracks-add {
  background: #2d2d2d;
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.1rem 0.5rem;
  font-size: 0.9rem;
  line-height: 1;
  cursor: pointer;
}

#tracks-add:hover {
  background: #3a3a3a;
  border-color: #444;
}

#tracks-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.track-card {
  background: #1f1f1f;
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  padding: 0.5rem 0.6rem 0.6rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.track-card-header {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8125rem;
  margin-bottom: 0.15rem;
}

.track-color-swatch {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  flex: 0 0 auto;
}

.track-name {
  color: var(--fg);
  flex: 1;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.track-card .track-toggle {
  display: flex;
  align-items: center;
  gap: 0.2rem;
  font-size: 0.7rem;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
}

.track-card .track-toggle input {
  margin: 0;
  cursor: pointer;
}

.track-card .track-delete {
  background: transparent;
  border: none;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1;
  padding: 0 0.25rem;
  cursor: pointer;
}

.track-card .track-delete:hover:not(:disabled) {
  color: #f66;
}

.track-card .track-delete:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.card-slider-row {
  display: grid;
  grid-template-columns: 4.5rem 1fr 3rem;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.7rem;
  color: var(--muted);
}

.card-slider-row input[type="range"] {
  width: 100%;
  margin: 0;
}

.card-slider-label {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.card-slider-value {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  color: var(--fg);
  font-size: 0.7rem;
  text-align: right;
}

.card-select-row {
  display: grid;
  grid-template-columns: 4.5rem 1fr;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.7rem;
  color: var(--muted);
}

.card-select {
  width: 100%;
  background: #2a2a2a;
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.15rem 0.3rem;
  font-size: 0.75rem;
}

.card-pair-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.card-pair-row .card-slider-row,
.card-pair-row .card-select-row {
  grid-template-columns: 2.5rem 1fr 2rem;
}

.card-pair-row .card-select-row {
  grid-template-columns: 2.5rem 1fr;
}

#canvas-mount canvas.resize-hover {
  cursor: ns-resize;
}

/* Collapsible Detection sub-panel ------------------------------------------ */
summary.subpanel-title {
  cursor: pointer;
  user-select: none;
}

/* Collapsible main Controls panel ------------------------------------------ */
#controls > #controls-details > summary {
  margin: 0;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
  list-style: none;
}

#controls > #controls-details > summary::-webkit-details-marker {
  display: none;
}

#controls > #controls-details > summary::before {
  content: '▸ ';
}

#controls > #controls-details[open] > summary::before {
  content: '▾ ';
}

#controls > #controls-details[open] > summary {
  margin-bottom: 0.75rem;
}

/* Mobile / tablet ----------------------------------------------------------
   Single column stack: Controls → Canvas → Tracks. Covers all phones (any
   orientation) and tablets up through iPad Mini landscape. */
@media (max-width: 1100px) {
  header {
    padding: 0.75rem 1rem;
  }
  main {
    grid-template-columns: 1fr;
    gap: 0.5rem;
    padding: 0.5rem;
  }
  body:not(.has-image) main {
    grid-template-columns: 1fr;
  }
  aside,
  section {
    padding: 0.75rem;
  }

  #controls { order: 1; }
  #canvas-mount { order: 2; }
  #tracks {
    order: 3;
    max-height: none;
    overflow-y: visible;
  }

  /* Touch targets ~36–40px tall */
  .transport button {
    padding: 0.6rem 0.75rem;
    font-size: 0.875rem;
  }
  .toggle {
    min-height: 36px;
  }
  #tracks-add {
    padding: 0.3rem 0.75rem;
    font-size: 1.05rem;
  }
  .track-card .track-delete {
    font-size: 1.25rem;
    padding: 0 0.5rem;
  }
  input[type="range"] {
    height: 28px;
  }

  /* Stack paired per-track sliders vertically */
  .card-pair-row {
    grid-template-columns: 1fr;
  }
}