You can even set Safari to automatically go into reader mode for all websites (I do this, then whitelist the sites/webapps). 9 times out of 10 this is much more readable and is darkmode by default.
You can also set reader mode automatically for just certain websites instead (i.e. whitelist vs blacklist); I do this for Bloomberg, Medium, WaPo, and others.
they almost certainly already know this and dont care