Still not seeing anything change. Getting something about @import preventing parallel downloads and using <link> instead.
And... I'm not really familiar with css at all, so I'm really sure what I'd be supposed to ask the staff. Last two times I was advised to ask them do something it turned out they couldn't anyway, so I rather have any changes in my won hands.
Then crop the white space on each side of this file and it should give the same view as using transparent.
As for why you need to import. Common.css only applies to the Monobook skin by default while Wikia.css applies to the Oasis skin. Importing them together allows the styling on Common.css to also be applied to the Oasis skin.
(Since apparently import simply is duplication elsewhere, I added the code manually to Wikia.css. This works too, right?)
Not exactly. Adding the code to both is duplication. Importing is keeping the code on one page and loading it on another. Duplicating the code isn't a great idea, especially if there are changes in the future. You might unwittingly change it for one skin and not the other.