User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4) Gecko/2008030714 Firefox/3.0b4 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4) Gecko/2008030714 Firefox/3.0b4 IFRAME does NOT respect absolute positioning stated in both external, internal and as an attribute. Reproducible: Always Steps to Reproduce: 1. Go to my testcase 2. The iframe should expand. 3. Actual Results: The iframe doesn't expand under firefox 3b4 Expected Results: the iframe to expand.
IFRAME is a replaced element and thus 10.3.8 applies: http://www.w3.org/TR/CSS21/visudet.html#abs-replaced-width <iframe ... style="... position:absolute; left:171px; top:0px; right:0px; bottom:0px;" ... 1. the intrinsic width in this case is 300px 2. no, both 'left' and 'right' have values that are not 'auto' 3. no, both 'left' and 'right' have values that are not 'auto' 4. no, margins are not specified and thus have the initial value zero 5. no, 'left' is not 'auto' 6. the styling is over-constrained, since the 'direction' is 'ltr' we ignore the specified value for 'right' The old layout in Firefox 2.x is a bug, per CSS 2.1. See bug 307102 and bug 412679 for reference. -> INVALID
I should say though that it is being discussed on www-style whether CSS 2.1 makes sense in this case: http://lists.w3.org/Archives/Public/www-style/2008Feb/0187.html so I guess we should fix this if the spec is likely to change... David?
Boris usually marks these issues as a duplicate of bug 410146. That should help to keep track of all these related bugs.