How to remove duplicate CSS?

Question

css

Tell me there is some tool for such a task:
There are 2 CSS files, one - main.css contains all the styles of the page. The other one is critical.css. There styles for fast loading of the first screen of the page. So main.css already contains the styles that are in critical.css, etc. when main.css is loaded, they are reloaded. To reduce the size of main.css, it would be logical to remove the styles that are already there from it.
How to do it? Of course, the "manual" option is not suitable.

Answer 1

uncss

Answer 2

https://habr.com/ru/company/ruvds/blog/477274/
https://habr.com/ru/company/ruvds/blog/477276/

Answer 3

cave

Answer 4

Webpack solves such problems at once