Hi Oscar,
You mention the following selector: `.orbeon .fr-grid .button
xfoms-Clickbutton`. Here, `button` is the class name you specified for that
control in the Control Settings dialog, so that part is correct. However,
`xfoms-Clickbutton` isn't correct; there will be no such class in the DOM.
Instead of trying to predict and visualize what the DOM looks like, I highly
recommend you just look at it with Dev Tools. And there you can also see if
your CSS works, and change it live to get the effect you need. I hope this,
or rather the Dev Tools, helps!