In that case I'd say the problem is exactly what you state
> knows essentially no CSS
The solution is quite obvious then too: learn some. It's not hard. Understanding the basics is a afternoon job. Diving a bit deeper a day, and learning about some often-used more in depth features like "responsive" or flexbox, another day. For a software developer/engineer that builds backends, CSS really isn't that hard.
That's not to say a basic CSS set and some explanation like in TLA, isn't useful.
It's my pet-peeve that in software development, I'm convinced we should understand the stuff that we work with. Not all, and certainly not everything in great detail, but enough to know where to find the info and details when working with it. From sysadmin to the concepts of cryptography and from accessibility to how an OS writes stuff to disk. Even if that means constantly learning.