Ask HN: How can I avoid getting mouse arm while doing webdev/front end work?

The Q may be a bit weird, but please stay with me. Before, I used to do mostly backend work. So I could spend all day in the IDE and mostly just see if the tests passed.

Now, I do a lot of frontend, which is not easily testable in the same way. I have to click back and forth, scroll a lot etc. to trigger the conditions I'm testing. All this I do with a mouse, and I'm really starting to feel it.

Any tips on a workflow that avoids using the mouse so much?