Re: first things first
@Maythil – If you’re on a Mac… download a copy of CSS Edit:
This editor makes it ridiculously simple to “reverse engineer” CSS code. In the “x-ray” mode you can click any element on the screen and it tells you what the container is (along with all of it’s parent elements). You can also bring up an “inspector” that will show you all CSS declarations that are affecting that element. And you can even modify the CSS and see the changes as you type the code. I’m not sure if there is anything similar for PC… but there must be.
I actually took a quick look myself using CSS Edit and the difference between profile pages and other pages seems to be that profile pages have two left sidebars with a fixed width of 138px (#optionsbar and #userbar) while the other pages have a single right sidebar (#sidebar) without any width defined (i.e. 100%). Meanwhile, #main is used on all pages and has a min-width of 680px. So unless you change some CSS code… the profile pages will always be at least 956px wide.
How did you change the CSS? One thing to bear in mind is that the default theme is fluid. It has min and max widths set. It sounds like you want a fixed width of 800px all the time (no bigger, no smaller… regardless of window size). So… did you remove the min/max on the body and change it to 800? Did you remove the min-width on #main and change it to… let’s say… 560px (allowing 120px each for those two sidebars in the profile)?
Anyway… as mentioned above… this is not a bug and has nothing to do with BuddyPress development. It’s just CSS 101. But I feel you pain. Hopefully the above is some help.
p.s. Did you look at Elgg during your evaluation? It has some features I need that BP currently lacks… but BP is clearly much superior otherwise.