How do I style the dropdown button in a Search Bar

Code Help HTML/CSS/JS
1

Question:
How do I style the dropdown button in a Search Bar?

I am running Microsoft Edge.
Repl link:
WorldCache

2

You can’t style the default dropdown button. You can make your own, by using flexbox.

3

From what I’ve heard, it is a Pseudo element which means you can edit, but I don’t know what that means.