Rated 4 out of 5 stars

Also, why doesn't my google page look black and magenta like yours? :/

This review is for a previous version of the add-on (1.0910).  This user has a previous review of this add-on.

Actually the image is just for demonstration purpose only, it is nothing to do with the theme. If you want to make your Google homepage like this:

You can simply download from the following link:
https://picasaweb.google.com/110789133670389722954/SmallringFXDarkThemeBackground

On Google's homepage, you can see "Change background image" on the right bottom corner, just apply it then it will be done.