:root {
  color-scheme: light dark;
  --border: #888;
  --bg: canvas;
  --fg: canvastext;
}

* {
  box-sizing: border-box;
}

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

.topbar {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}

.topbar h1 {
  font-size: 1.1rem;
  margin: 0;
}

.topbar label {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.9rem;
}

.frame-position {
  margin-left: auto;
  font-variant-numeric: tabular-nums;
  opacity: 0.8;
}

.workspace {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  align-items: flex-start;
}

.canvas-area {
  flex: 1;
  min-width: 0;
}

#image-container {
  position: relative;
  display: inline-block;
  max-width: 100%;
  border: 1px solid var(--border);
  line-height: 0;
}

#frame-image {
  display: block;
  max-width: 100%;
  height: auto;
  user-select: none;
}

#bbox-layer {
  position: absolute;
  inset: 0;
  cursor: crosshair;
}

.bbox {
  position: absolute;
  border: 2px solid var(--bbox-color, #ff4136);
  background: color-mix(in srgb, var(--bbox-color, #ff4136) 15%, transparent);
  cursor: move;
}

.bbox.selected {
  outline: 2px dashed white;
  outline-offset: 2px;
}

.bbox .bbox-tag {
  position: absolute;
  top: -1.3em;
  left: -2px;
  background: var(--bbox-color, #ff4136);
  color: #fff;
  font-size: 0.75rem;
  padding: 0 0.3em;
  white-space: nowrap;
}

.bbox .bbox-handle {
  position: absolute;
  right: -5px;
  bottom: -5px;
  width: 10px;
  height: 10px;
  background: var(--bbox-color, #ff4136);
  cursor: nwse-resize;
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-top: 0.75rem;
}

.sidebar {
  width: 220px;
  flex-shrink: 0;
}

.sidebar h2 {
  font-size: 1rem;
  margin: 0 0 0.5rem;
}

#class-list {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  margin-bottom: 1rem;
}

.main-class-label {
  font-size: 0.8rem;
  opacity: 0.7;
  margin-top: 0.5rem;
}

.class-chip {
  display: block;
  width: 100%;
  text-align: left;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--border);
  border-left: 6px solid var(--chip-color, #888);
  background: none;
  color: inherit;
  cursor: pointer;
  font-size: 0.9rem;
}

.class-chip.active {
  background: color-mix(in srgb, var(--chip-color, #888) 25%, transparent);
  font-weight: 600;
}

.hint {
  font-size: 0.8rem;
  opacity: 0.75;
  line-height: 1.4;
}