Don’t use custom CSS scrollbars

Scrollbars are part of the area of the browser that is outside your scope of concern.

Similar to “you break it, you buy it” I like this theme Eric proposes for working with the browser: “you modify it, you’re responsible for it.”

If you modify the Operating System scrollbar’s appearance, it is now on you to ensure that it meets Web Content Accessibility Guidelines criteria.

If you override X default functionality, it is now on you to provide all defaults the browser does (e.g. prevent default form functionality). That kind of awesome responsibility might make us stop and question our choices a little more often.

When you override this expression, you’re indirectly communicating that someone’s personal preferences are less important than your own visual sensibilities.