Thread:Extension talk:Header Tabs/Version 7.0: css-modification: works in MediaWiki:Vector.css but nor in skins/headertabs.css

I describe an experience for two reasons 1) maybe someone else has the same problem and finds this solution helpful 2) maybe someone else finds my solution strange and has a better proposal

In earlier versions and under monobook-skin I used to accomodate the css-definitions in the file

For some reason this did not work with version 7.0 under vector-skin. My solution: I copied the file  into the MediaWiki-page and got the previously used layout.