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.