This has been requested for.. ever 

you can fudge it with Arc browser ish

Agreed. I'm ok with UI redesign, but the stark contrast between the darker grey of Jamf Pro 10.x and the white of 11.x is too much. I guess this was done for readability purposes as explained in the notes, but still.... don't hurt my eyes!

Pretty sure this is going to be a feature soon.  They talked about it at JNUC. 

I don't know who at Jamf is reading this, but dear sweet jeebus, I'm down on my knees begging you to PLEASE implement a dark mode. I get light sensitive migraines, so really bright UIs can be like a dagger through my brain.