When I click the slider or move it in chrome it gets highlighted with a box. If I click drag and let go the highlighted box persists until i click elsewhere on the page. On firefox the same functionality does not highlight it at all no matter what you do, which is what I think is intended. Sidenote, the font for that same page looks different in chrome vs firefox, anyone know why that would be the case?
This is usually part of the keyboard accessibility features of the browser - element highlighting allows a user to access the components of web page with keyboard only (usually with tab) and in this case adjust the slider with arrow keys.
I’m not a web developer, but I think it’s generally considered good practice to have these components keyboard accessible, so I’d argue that the way Chrome renders it is correct. Here is what it looks like in Safari:
