Ui improvements

Several visual improvements to the UI
I had shortened these because this text doesn't fit in the panel horizontally, on my OS at least.

Also, is it really a reference level? To me reference level is that thing that dBm value we get in our context packets that jumps up and down. It's also not obvious (to me) that reference level means the top of the display, or that it's associated with "minimum level" in any way.