Oh man how do I find someone like this. As a backend/infra dev I respect, fear and loath (in the reverse order) css. If you can find your complement(s) there is nothing like it!
I can pop open a web inspector and make a bunch of changes, but that's the easy part. Unlike when I'm working on my own, far simpler side projects, I can't just switch over to VS Code and paste the changes in to the requisite selectors: Assuming I have a local environment set up (no easy feat itself!), now I have to track down React components, find their stylesheets, perhaps follow some leads out to other stylesheets coming from different libraries...
It's all something I'd love to get to a point of familiarity with in my next job (which I am currently looking for!), but the upfront time investment (in part by the developer to explain the repo to me) has kept it just out of reach so far.
You could use AI tools to emulate a co-worker putting you up to speed probably nowadays.
IIRC they called it "design engineer". Not sure where in the org structure they fell under (i.e., whether they reported to design managers or engineering managers, i think it might've been under engineering managers), but I worked with a few of them directly, and it was amazing.
I was working on the front-end of a web app, so I did quite a bit of design implementation handed to me by designers. But for some very tricky styling or just in general, occasionally, design engineers would come out to help.