Can anyone help me restore my background to white?

I'm in the middle of designing a website (my 1st attempt) and was making some small changes to a plugin on my index.php in order to create a Full-browser Image. It didn't work, but having also changed my #menu background-color on CSS page from white (Hex #fff or RGB 255;255;255) to light grey (#f7f7f7 or 247;247;247) somehow the background color on my Windows Word, Notepad, My Docs, Explorer and Mozilla browser also changed to the same grey.

I have since reversed the HTML changes without success and Display Properties >> Appearance >> Advanced >> Window is set to white so I’m thinking a file on XP dealing with backgrounds needs to be reset back to the default white. If so I’d be able to escape from this horrible grey haze. Any solutions very much appreciated. Thanks.