What is the UI of MongoDB Compass written in?

Question

JavaScript

I liked the look, it would be gorgeous for corporate forms, dug inside, it turned out to be written on the AmpersandJS framework (interesting, by the way, I heard about it for the first time), but it’s not clear what the UI is on. Something similar to bootstrap, but prettier and more compact.
Maybe some kind of their own development based on it, but suddenly there is such a ready one.
PS Who knows more attachments for Electron with a beautiful design - share.
PPS After a long search, I came to the conclusion that it is easier to write the interface yourself, almost all libraries are forced to delve into and use their approach, the components also contain glitches or vice versa do not contain what you need (it's a shame when 90% is there and you bump into the very necessary 10% and have to be rewritten).
So far I've settled on Quasar, but if you write a commercial application, it's easier to order a UI-kit layout designer and apply it to React / Vue