I have created a username and pw and placed in a Secure Note. You can turn off the Under Construction mode after logging in. I now have two issues and cannot back up to where I took a wrong turn.
New Issue: The navigation bar is no longer colored. I use to have a black bar with white menu titles. Now, it's just menu text.
Original Issue: I could not get the bar height to change. It remained the same height no matter what number I entered into Customize > Header > NAVBAR > Navbar Top Height (px). I wanted to make it smaller. No change, so I made it double just to see if it would change, but it didn't, which made me wonder if I was in the right section since it didn't change either way (I thought there might be a minimum size).
All troubleshooting items were attempted, where applicable.