Is it possible to render $\LaTeX$ in Safari?
I haven’t tried them, but there are some bookmarklets written by a user on the Mathematics Stack Exchange which sound like they do roughly what you’d want:  Should chat have TeX support?

In particular, the “render MathJax” bookmarklet sounds exactly like what you want:


  render MathJax installs MathJax and renders $\LaTeX$ once per execution. This is intended for use on web pages where the contents of the page are static.


These were originally written for Math.se users to get MathJax rendering in their chatroom within SE spending development time adding it to chat, but I see no reason why it wouldn’t work on an arbitrary webpage (and indeed, it seems to work like that on the installation page).