RenderBlock (positioned) {DIV} at (0,0) size 800x600 [bgcolor=#006400]
layer at (0,0) size 800x1
RenderBlock {DIV} at (0,0) size 800x1
- RenderHTMLCanvas {CANVAS} at (0,0) size 1x1
+layer at (0,0) size 1x1
+ RenderHTMLCanvas {CANVAS} at (0,0) size 1x1