Yeah, this is using a new feature[1] only available in Chrome so far. Mozilla is positive[2] about the specification, so we should see it in Firefox eventually,

Yeah, this is using a new feature[1] only available in Chrome so far. Mozilla is positive[2] about the specification, so we should see it in Firefox eventually, pending an implementation. [1]: https://developer.chrome.com/blog/a-customizable-select https://developer.chrome.com/blog/a-customizable-select [2]: https://github.com/whatwg/html/pull/10548 https://github.com/whatwg/html/pull/10548