If browsers innately and sanely supported default / assignable CSS that ... might be workable. I'd also much prefer browser's default styling was far more sane.
As things stand, some browsers (and, good news, those used by the overwhelming majority of desktop visitors) support CSS-management extensions such as Stylus.
But those don't work for all browsers, and aren't available in particular on Google Chrome/Android.
I've tweaked my own browser's default stylesheet in the past, and currently use a customised Reader View style for Firefox. Both are problematic, and changing the browser's default styling is probably best avoided these days. My Reader Mode view breaks somewhat and sometimes, but when it hits right, it's much better than stock.
As things stand, some browsers (and, good news, those used by the overwhelming majority of desktop visitors) support CSS-management extensions such as Stylus.
But those don't work for all browsers, and aren't available in particular on Google Chrome/Android.
Firefox/Android does support Stylus, with some limitations: <https://old.reddit.com/r/firefox/comments/qgsqob/stylus_for_...>.
Apparently not for Safari / iOS: <https://github.com/openstyles/stylus/issues/299>
I've tweaked my own browser's default stylesheet in the past, and currently use a customised Reader View style for Firefox. Both are problematic, and changing the browser's default styling is probably best avoided these days. My Reader Mode view breaks somewhat and sometimes, but when it hits right, it's much better than stock.