User-Define Css

Hi, I have a simple request.

I want to create a sub categories text link on all my categories. I created a Catalog tree block in the Categories Main Layout.

What I got is the sub categories in a column. What can I add in the User-define CSS to display in a single row?

See my attached image for details

Thanks in advance.

No image was attached to the message. If would be good, if you provide us with the URL as well