When XHTML Strict is considered to be a proper markup that works across all platforms, my webpage that’s in XHTML 1.0 Strict does render differently in Quirks mode.
Am I doing something wrong? The page perfectly validates in W3C!
EDITED FOR THOSE WHO REFER TO THIS QUESTION AFTER THE LINKED PAGE HAS CHANGED:
The original markup contained nested DIVs with floated elements. I did not specify ‘width’ property for all possible elements and that somehow triggered a difference in rendering in old browsers including IE 7.0.
Not sure exactly what your question is but quirks mode is intended for legacy web pages and usually user agents support oldschool layout techniques that were used in tabular layouts. Modern standards based web pages which are in standards mode do not rely on those.
A modern layout might not look correct in quirks mode just simply because it isn’t built for it. Or did I misunderstand the question?
Oh and even if your page is perfectly valid that doesn’t mean your layout is “perfect” or that it will be rendered by all browsers the same exact way.