.canvas-stage {
  position: relative;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  background:
    radial-gradient(
      circle at center,
      var(--viewer-stage-glow),
      transparent 55%
    ),
    var(--color-canvas);
  touch-action: none;
}

#main-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
  cursor: grab;
}
#main-canvas[data-mode="measure"],
#main-canvas[data-mode="scale"] {
  cursor: crosshair;
}
#main-canvas[data-mode="roi"] {
  cursor: crosshair;
}
#main-canvas.is-dragging {
  cursor: grabbing;
}

.canvas-instruction {
  position: absolute;
  z-index: var(--z-toolbar);
  top: var(--space-3);
  left: 50%;
  transform: translateX(-50%);
  max-width: min(560px, calc(100% - 32px));
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: 8px 11px;
  border: 1px solid var(--viewer-instruction-border);
  border-radius: var(--radius-md);
  color: var(--viewer-instruction-text);
  background: var(--viewer-instruction-background);
  box-shadow: var(--viewer-instruction-shadow);
  font-size: 12px;
  pointer-events: none;
}
.canvas-instruction[hidden] {
  display: none;
}
.instruction-mark {
  flex: none;
  min-width: 34px;
  padding: 4px 6px;
  border-radius: 999px;
  color: var(--viewer-instruction-mark-text);
  background: var(--viewer-instruction-mark-background);
  font: 750 11px/1 var(--font-mono);
  text-align: center;
}
.canvas-instruction.is-pending {
  border-color: var(--viewer-instruction-pending-border);
}
.canvas-instruction.is-pending .instruction-mark {
  color: var(--viewer-instruction-pending-text);
  background: var(--viewer-instruction-pending-background);
}

.drop-zone {
  position: absolute;
  inset: 50% auto auto 50%;
  transform: translate(-50%, -50%);
  width: min(420px, calc(100% - 40px));
  min-height: 230px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  border: 1px dashed var(--viewer-drop-border);
  border-radius: var(--radius-lg);
  color: var(--viewer-drop-text);
  background: var(--viewer-drop-background);
  transition:
    border-color var(--transition-normal),
    background var(--transition-normal),
    transform var(--transition-normal);
}
.drop-zone:hover,
.canvas-stage.is-dragover .drop-zone {
  border-color: var(--viewer-drop-hover-border);
  background: var(--viewer-drop-hover-background);
}
.drop-zone.hidden {
  display: none;
}
.drop-zone-mark {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  border: 1px solid var(--viewer-drop-border);
  border-radius: 50%;
  color: var(--viewer-drop-mark);
  font-size: 28px;
}
.drop-zone strong {
  font-size: 15px;
}
.drop-zone span {
  color: var(--viewer-drop-muted);
}
.drop-zone small {
  margin-top: var(--space-2);
  color: var(--viewer-drop-subtle);
  font-size: 12px;
}

.canvas-toolbar {
  position: absolute;
  z-index: var(--z-toolbar);
  left: 50%;
  bottom: var(--space-4);
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 3px;
  padding: 5px;
  border: 1px solid var(--viewer-toolbar-border);
  border-radius: var(--radius-md);
  background: var(--viewer-toolbar-background);
  box-shadow: var(--viewer-toolbar-shadow);
}
.canvas-tool {
  min-height: 40px;
  border: 0;
  border-radius: var(--radius-sm);
  padding: 7px 10px;
  color: var(--viewer-toolbar-text);
  background: transparent;
  white-space: nowrap;
}
.canvas-tool:hover:not(:disabled),
.canvas-tool.is-active {
  color: var(--viewer-toolbar-active-text);
  background: var(--viewer-toolbar-hover);
}
.canvas-tool.is-active {
  box-shadow: inset 0 0 0 1px var(--viewer-toolbar-active-ring);
}
.canvas-tool.square {
  width: 40px;
  padding: 0;
  font-size: 20px;
}
.canvas-tool kbd {
  margin-left: 4px;
  color: var(--viewer-toolbar-key);
  font: 12px/1 var(--font-mono);
}
.toolbar-divider {
  width: 1px;
  height: 24px;
  margin: 0 3px;
  background: var(--viewer-toolbar-border);
}

.analysis-overlay {
  position: absolute;
  z-index: 9;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  color: var(--viewer-overlay-text);
  background: var(--viewer-overlay-background);
  backdrop-filter: blur(3px);
}
.analysis-overlay span {
  color: var(--viewer-overlay-muted);
}
.analysis-spinner {
  width: 34px;
  height: 34px;
  margin-bottom: var(--space-2);
  border: 3px solid var(--viewer-spinner-track);
  border-top-color: var(--viewer-spinner-accent);
  border-radius: 50%;
  animation: spin 0.9s linear infinite;
}
@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}