"Want the same functionality across all Browsers? Better use Js." This is not the point. The point is some developers just include big Javascript files because

"Want the same functionality across all Browsers? Better use Js." This is not the point. The point is some developers just include big Javascript files because they don't know what other methods and options there are. I have seen developers include Javascript to 'fix' things across browsers but it made things worse because the `let` keyword was not supported in some browsers at that time. So it is not about if you should use Javascript. It is about the fact a website or webapp can and should be fast. But when a developer does not know about the technical aspects we will end up with multi-megabyte pages that take 10 seconds to complete. -- About the `position: sticky`: it is not smart to promise a client a pixel perfect experience across all browsers (unless they want or need to and will pay the extra price). In the case of a sticky header you can support all modern browsers with two lines of CSS (`position` and `top`). The other 6% won't have a sticky header but still a perfectly working website. So imho you did not caught a mistake but a real world example.