Wordpress banner / header color

I was playing around with Wordpress + Commentpress (a plugin) and I at some point intentionally changed the header color (indicated by the arrow below).

However, for the life of me I can't find the option to change the color or remember how I changed it, and I need to change it to some other color. I'm sure I didn't do this via manipulating the CSS file directly. There was a UI control somewhere that I used.

Any idea how to change the color again (preferably without directly manipulating the CSS)?