why the CSS alignment is different from Firefox3.0.11 and Firefox 3.5

Question

why the CSS alignment is different from Firefox3.0.11 and Firefox 3.5?

Answer 1

May be because of an upgrade to the gecko engine(which is used for rendering pages by Firefox) from 1.9 to 1.91 in Firefox 3 to 3.5 .

Answer 2

The rendering engine changed between 3 and 3.5. They either introduced a bug which resulted in the change (assuming the 3 rendering is correct and the 3.5 rendering is incorrect), or they fixed a bug which resulted in the change (assuming the 3 rendering is incorrect and the 3.5 rendering is correct).

Some things I'd suggest:

• First ensure your CSS is well-formed and conforms to standards. Malformed or non-standard CSS may be interpreted differently by different rendering engines.
• Produce the smallest, self-contained sample that demonstrates the problem and edit your question and include it here.
• Examine the results of your CSS in lots of other browsers (IE 6, 7 & 8, Opera 9 & 10, Safari 3 & 4, Google Chrome). Does the result of Firefox 3 or 3.5 more accurately reflect the results in a majority of other browsers? Like it or not, browsers interpret the CSS spec differently, sometimes the best you can do is use CSS that "looks close" in as many browsers as you need to support. The fact that two versions of Firefox produce different output demonstrates that sometimes you can't even depend on even a single browser vendor to render the same CSS the same way. This situation also applies to IE 6, 7 & 8, Opera 9 & 10 and Safari 3 & 4 - all of which I have noticed various degrees of rendering differences in.
• Search Bugzilla@Mozilla for any bugs related to your problem. Something like this. The problem as you can see with the included search is that it matches lots of bugs. This is why it is important to be as specific as possible when describing your problem.
• Find another way to accomplish your layout that does not demonstrate different behaviour in Firefox 3 and 3.5.

I hope some of this helps.