How to remove underline from Generateblock buttons?

Hi, since a couple of months, maybe half a year, my generateblocks buttons does have underline on mouse over. I am almost certain they did not have that earlier (?) and I do not want any underline on buttons.
How can I remove the underline? But not change anything else. I can´t seem to find the right CSS code.

You can see example of buttons in the url added to the private info below.

Bonus question:
Is there any positive win in speed or so to change all "old" buttons to the new type without the "extra" container, that came with the latest update?