Permanent Inspect Element

This extension lets you save the changes you make to a static web page using Inspect Element to remain there even after you refresh the page. So if you want to modify a web page to make it easier for you to read, or to remove an intrusive banner, you can do that, and you wouldn't have to re-do it every time you visit the page again.

Of course, this only changes the content of the page on *your* computer and not the website itself.