Screen jiggles when I edit the title/name colors

When I add a new member, the text is dark grey. I need to change it every time (don’t see any way to set default colors). When in the screen that pops up with the color choices, the screen shakes/jiggles until I exit. This is a recent development. I see that this hasn’t been updated – is it going to languish? Is there something out there better? I’m using toggles on the same page, not sure that matters. (This is my first site dev with a default WordPress theme and oy, it’s painful.)

The page I need help with: [log in to see the link]