Consider this document:
<!DOCTYPE html>
<html style="filter: invert(90%);">
Some text
</html>
Note that in this document the <html> has a transparent background but a
black text color by default in browsers. The canvas has a white
background by default in browsers.
The spec text says:
Conceptually, any parts of the drawing are effected by filter
operations. This includes any content, background, borders, text
decoration, outline and visible scrolling mechanism of the element
to which the filter is applied, and those of its descendants.
The canvas background is not part of the "element to which the filter is
applied", so per the current spec this document should render with light
gray text on a white background.
This is what Firefox does. Chrome instead seems to make the canvas
background black.
Which behavior do we want here? What about other cases of filters being
applied to the root element? Do we want to effectively propagate these
filters to the viewport, like CSS does with 'overflow' and backgrounds
on the root element?
-Boris
