class names changes, causing a lot of work

I have updated from joomla 3 to 4 and also the template Bike to the new one. There are more thann 200 articles on the side that use the class uk-button and others starting with uk-button-xxx. In the new template you used btn causing all the classes not working anymore.

What can I do to change all of them faster instead of opening and changing 1 by 1?
Regards
Roell

Add the code of the class via css in the template options at custom code. This changes the class globally.
If you give us a link to the page, we can also give you the code.