This user style simply forces the sans-serif from your browser configuration on all the text on a site (except on headlines, if the site has specifically styled them so – where a serif face is OK anyway). I use it to strip sites of Arial (eg. Google) or make designs readable that use not only tiny fonts but also serif fonts – often a sans-serif in the same point size will be readable on a screen where a serif is not, simply due to the low resolution of screens compared to paper.

This style is *meant* for editing: the list of sites I included is just an excerpt from the list for which I use it, and you should customise it to include whatever sites bother *you* with their awful typographic choices. You could even edit it to make it enforce your default serif… or edit it to enforce any *particular* typeface of your choice. Get wild, use it/abuse it as you wish.