@feld @gsderp I use Bookmarklets / GreaseMonkey / TamperMonkey scripts to improve the overall accessibility and usability of sites.
Eg. a semi-dark reader with bigger font sizes for selected or all sites whenever I need it. Some sites tend to eg. enforce nasty unreadable sizes, or use garbage contrasts etc.
Its not that I'm near blind, but I'm both strongly sight-impaired and am light-sensitive in combination with synesthesia, so overload gets induced quickly if there is .. interference.