This HTML demonstrates awful text rendering.
should render as
If the superscripts and subscripts render as smaller versions of normal characters, the browser should be modified to render the former text as latter, or give an option. Fake superscripts and subscripts are not customizable by the font designers.
should render like this
and not in color. (Proof: Notepad is the reference for rendering plain text (it supports bitmap font in all Microsoft Windows versions, for example); if the font is changed to DejaVu Sans, the characters render like in the image, which is correct.)