If there is no such ancestor, the containing block is
the initial containing block.
The containing block in which the root element lives is
a rectangle with the dimensions of the viewport, anchored at the canvas origin
for continuous media, and the page area for paged media.
The containing block for absolutely positioned content with no positioned
ancestor is the viewport / page area. When sized to 100% height/width, the
content will cover the html margins/borders.
There should be no red on this page.
End test t1001-abs-pos-cb-09-b-p.xht