Inline small css

Google page speed is advising to inline small css:
The following external resources have small response bodies. Inlining the response in HTML can reduce blocking of page rendering.

https://www.infolotnicze.pl/ should inline the following small resources:

https://www.infolotnicze.pl/wp-content/plugins/search-by-category/sbc-style.css

Any hints how to do this?

http://ww.wp.xz.cn/extend/plugins/search-by-category/