It's a file containing customisations to CSS styles. Copy the text above into a new file, save it somewhere with a .css extension, and set it up in Safari > Preferences > Advanced.
" not a such a critical feature that it will hold things up. But we'll look into it. "
It's reasonable to assume that the current exceptional change of appearance of polls (seen with vBulletin) is a side-effect of preparations for better appearances with XenForo. If that's true: I should not expect detailed public explanations about such things.