Based on some of the themes I have seen, I can’t imagine that it isn’t possible. So you could download and pick apart the css of various themes to try to figure it out.
Or, you may be able to find something here in this extremely helpful collection that @Klaas originally put together: "How to achieve" CSS code snippets
If you are knowledgeable in CSS , you may have luck using the Developer Tools to locate helpful information through experimentation.
Hope this helps. Wish I knew enough to tell you more. There was a CSS community talk scheduled for yesterday by @Lithou that was probably very good. I am looking forward to checking it out if there is a recording.
Thanks.