How would I go about changing the look of dcc.Dropdown?

Hi there

I am using some dropdowns about my chart, which currently look like this:


I want to change the look of them and generally make them look slicker, like this:


How exactly would I go about this?

Not looking for exact specific on achieving that specific look but a more general point in the right direction. Presumably this is something that can be achieved with CSS? If so, is it as simply as creating some custom CSS, and then applying that custom classname to the dropdown component? Or is it more involved than that?

Any advice would be much appreciated.