Increase spacing between Window icons / tasklist items (no labels)

Is it possible to increase the spacing between items/buttons/icons in Window buttons / tasklist plugin?

I am not using the labels and at the moment it looks like this on my system:

I find it very annoying to work with because they are so close to each other.

I have actually spent some time trying to find a solution for this (checking the plugin settings, editing gtk css and even trying to edit the C source code directly), to no avail. Unfortunately I also don't have much knowledge of css or gtk, but if you know that it can be done and it isn't too complicated let me know where I need to look and I will try.

Using XFCE 4.16