Where to find this particular CSS Code or Image?

[FatalLulz]

Hey,

I'm making some edits to a CMS (Uber3/Illumin) I changed the topbg image, but where it says user's online in the top right it still shows the original blue colour. I found where to change that, but if I make it backround-color: transparent; it shows up like this Screenshot by Lightshot (in the corners it's a grey colour #e0e0da.)

I've searched all CSS Files, looked over all images but can't find anything to do with that colour. It might be an image because if I make the actual white part transparent, then it shows up like this: http://prntscr.com/11bbjb

Using web-gallery v2 (came with the cms) All help is welcome :)

- Cheers.

[MentaL]