Better looking MIDI menu

The MIDI menu is currently kind of aesthetically displeasing in that it doesn't look as good as the other visual elements in the application. Let's make it prettier!
<img width="908" alt="Screen Shot 2022-10-04 at 17 40 00" src="https://user-images.githubusercontent.com/1531144/193935373-1bafab10-912b-44d4-b214-e4cfb021487d.png">
