This is a thing I made using CodePen and jQuery. I guess I'll call it "jQuery select box plugin" or something like that.
I prefer to use native form elements as much as possible. But sometimes you want to spice things up and customize your form, but select boxes are really not very customizable.
Creating your own select box can be tricky. A simple dropdown list is easy enough, but if you insist on creating a custom select box you should make sure it works the same way a native select box does. That’s where it gets complicated.
Accessibility is the major thing. You must make sure you can control it using just your keyboard, and have it behave the way you would expect a native select box to behave.
Try using both select boxes above, and notice that they behave pretty much the same.