If you’re not being sarcastic, why limit yourself to only one thing? If you’re working on some amazing UI with tons of CSS animations and a full audiovisual experience, and it takes intimate knowledge of everything frontend, I guess it would make sense. But if you’re just making internal CRUD apps, I don’t see a reason why a given domain is special enough to have its own job title.
3Blue1Brown on youtube has amazingly good visual explanations for various math concepts. Helped me out a lot when I was having trouble with calculus. It doesn’t help specifically with memorizing theorems or anything, but provides a good conceptual framework to start with. https://www.youtube.com/c/3blue1brown