userstyles and userscripts for sbs frontends
files in haloopdy/ are compatible.
the userjs and usercss settings can be found in User tab of sidebar -> Developer Options
you can use https://pchicken.github.io/collection to get what you want nicely
files in twelve/ are compatible.
there are no userjs and usercss settings, so use browser extensions.
for firefox and chromiums (including edge), i recommend violentmonkey and stylus