To the web developers out there… I was reading this article about Sprite Optimization which is basically about creating a big image with all the graphical bits of your interface on it and then using css to clip and display only the relevant pieces.
In theory (and jundging by what I read.. in practice too) this makes your site load faster. I know that WordPress does this in places in thier admin interface.
Although reading the article, they do point out that for somethings doing it this way massively complicates matters.
I think I would split things up a bit, have one file for icons and perhaps another for borders and UI elements and maybe another for buttons or something like that.