I need to generate a error 404 for all url of my website who contain a specific attribute inside.

In fact I have many url who contain the attribute ?fontstyle=f-larger AND ?fontstyle=f-smaller and I would like find a solution for let me generate 404 error when trying to access to this kind of url.

If is not possible maybe I can redirect to a fake/inexistent url like www.site.com/fake.html who will result in a error 404...but I did not see how to do using .htaccess...

any clue please ??