Comment by grepular

Using a style element should have worked too. The HN CSP policy has unsafe-inline which covers both of these things.

Perhaps your problem wasn't with CSP at all, but something else. Maybe a CSS specificity issue?

[edit] - Yeah, I just created this bookmarklet and it worked fine:

javascript:(function(){s=document.createElement('style');s.textContent='*{font-size:20px}';document.head.appendChild(s)})()