I know this question has been asked and answered before, but the solution that I’ve come up is only half working.
I was able to get the CSS settings I wanted in real-time using the developer console, but the custom css class is losing out when displaying the field editor from the saved Skuid page.
I’ve had to use !important after my value in CSS to not get overridden by the Skuid theme. You will get an alert, in the CSS editor, but it’s worked for me when nothing else has.
Not sure if it will help anyone, but I managed to brute force this, by giving the field my own CSS name AND overwriting the existing CSS. Messy, but it worked: