fix: the picture of the CImage is not clear

src/views/bigscreen/ast/core/widget/CImage.vue

@@ -94,7 +94,7 @@ export default {
         height: `${height}px`,
         'font-size': `${Math.min(width, height) / 3 | 0}px`,
         'border-radius': `${radius}px`,
-        'background-image': !this.isEmpty && this.isNormal ? `url(${getThumbnailUrl(this.img)})` : 'none'
+        'background-image': !this.isEmpty && this.isNormal ? `url(${getThumbnailUrl(this.img, 'size')})` : 'none'
       }
     },
     className () {