[FEAT] PNG export fix

src/composables/useExportLayers.ts

@@ -23,7 +23,8 @@ export const useExportLayers = (layersRef: Ref<Layer[]>, columns: Ref<number>, n
     // Otherwise, calculate from sprite dimensions across ALL layers (same as canvas)
     // This ensures export dimensions match what's shown in the canvas
     const { maxWidth, maxHeight } = getMaxDimensionsAcrossLayers(layersRef.value);
-    const allSprites = getVisibleLayers().flatMap(l => l.sprites);
+    // Calculate negative spacing from ALL layers (not just visible) to keep canvas size stable
+    const allSprites = layersRef.value.flatMap(l => l.sprites);
     const negativeSpacing = calculateNegativeSpacing(allSprites, negativeSpacingEnabled.value);
     return {
       cellWidth: maxWidth + negativeSpacing,