Hi Mindset, the code in there looks like it's already setting a white background.

What version of MoI are you using? I just noticed in the path you wrote:
%AppData%\Roaming\Moi\ui\customui\-84 Snapshot.htm

is that path really where you've got it? For MoI v4 it should be a .js file in %AppData%\Moi\startup and for v3 it would be in the install folder's UI subfolder not in appdata...

- Michael