The unusual browser feature I use most is Reader Mode.
SO MANY STUPIDLY DESIGNED WEBSITES!
Reader Mode: "Here is the main text in a sensible typeface at a reasonable size with high contrast and appropriate margins."
There should not be a need for Reader Mode. RM's utility is a solid indictment against web designers.
Look at your site-intended-to-convey-textual-information with Reader Mode. If it breaks, fix that. If the page is suddenly much easier to read... you have work to do.
Typeface.
Size.
Contrast.
Margins.