Makes the start page (default homepage for firefox) dark. Works for google.com/firefox, so if you have some other url (with language/location stuff added to it) you will have to change it for this style to show up. I'll add support for the default url later. I'm too lazy to look it up.

All content is free to use. I'll be adding a sample style with a different background so you can customize your background in case you dont like dark.