Strange background behaviour, % of what ?

[DigitAlex]

I have here something I can't manage to find out.

There are multiple absolute positioned divs, and the innermost of one set has this simple CSS rule applied to it :

background:#F5F5F5 url(load.gif) no-repeat center fixed;

The problem in FF and IE is the same, you would think that the background picture would be centered because 'center' was specified, but it's not the case !

the background is behaving as if I used 60% from the left....

and to achieve 'about' the right center position, i have to use

background:#F5F5F5 url(load.gif) no-repeat 47% fixed;

I know about some strange things when using percentages for positioning, be careful to know a percentage of what it will be and so on, but here, no clue at all...

I'm not posting a sample right away because the problem is kinda buried in a lot of stuff, but well if it comes to it I can post something...

[DigitAlex]

up...

[DigitAlex]

both produce the same position which is not right, same if I put a div inside that one and try to center it, same result...