can’t make header bg transparent?

I have header .png with clear background so that users can see the underlying background image of the site. But wordpress/dynamic news won’t allow me to make header-wrap div transparent. It just keeps defaulting it to solid white #fff.

Several years ago I used this theme and was able to easily make direct edits to the stylesheet to solve things like this. Now I guess they made some new editor and you can’t do that? It’s really frustrating and has created a lot of unnecessary steps and wasted time for me.

Any advice would be appreciated.