CSS .slidetab Height/Width configuration

Greetings!

First off, thank you very much for this great module - this certainly adds value to a Drupal installation!

Secondly, I am fighting with customizing the CSS for the slidetab - with little success as I may add:

While I can add a background image and modify the width through the padding property, the tab seems to totally ignore any Width and Height properties.

Any advice on that?

I attached two screenshots for the kind of layout I am trying to achieve.

Thanks in advance!