How to undo clear css rule for a website

I cleared the CSS selector of a page and unfortunately the whole website breaks.
Please how can i undo clearing CSS selector of an element with brave browser?

Hi @Excellent, welcome to Community!

When you say:

I just want to confirm, did you clicked Clear CSS rules for this site, or did you click on Block element?

Also, can you provide me with a URL to the website the broke?

Facebook.com using a facebook lite extension

I cleared the css just as you have shown in the image

Can you give more detail on what you mean by: