FF3 WinXP != FF3 Ubuntu - why?

Question

I've got a website that I've just uploaded onto the interwebs, and it's displaying differently using Firefox 3.0.1 on Ubuntu and WinXP.

Two things I've noticed on Ubuntu:

1. The favicon is missing
2. The background color isn't displaying (it's set in the stylesheet)

What have I done wrong? The CSS file is being fetched under Ubuntu, so why isn't it applying all of the stylesheet, just the bits it likes? And why isn't the favicon displaying? Are they the same problem?

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The answer on the background color: invalid HTML. But I'd love for someone to explain why it works under Windows and not Ubuntu.

The answer on favicon: previously, there was no favicon. The browser cached the lack of favicon. Clear the Firefox cache, and all is well.

Answer 1

I would first suggesting getting you html and css code validated. If there are any errors in your markup, these can cause errors in the rendering.

• CSS Validator
• HTML Validator

Answer 2

I've also run into differences between FF3 on WinXP and FF3 on OS X (mostly with CSS positioning). The CSS and HTML both validated properly, but I was never able to figure out why there was this difference. I would think that the rendering engine would be the same, but apparently there are at least a few subtle differences.

Answer 3

I agree.. there are subtle differences between the two operating systems. Part of this is just font sizes and how line height and letter spacing is determined. So much of page flow is based on these whitespace elements interact with other page elements.