FYI, with latest version of Curtains 1.19, the Chrome/Edge browser styling option seems to be incompatible with the Microsoft Edge Startup Boost feature. Tested with Edge Version 91.0.864.59 (production) on Windows 10 19043.1081 (21H1).
According to Microsoft, Startup Boost keeps Edge partially running in the background when the browser is "closed" to increase perceived launch times. This "closed but not closed" state seems to mess with the skinning logic somehow, and the result is that the Edge title bar just defaults back to the Windows accent color.
Not sure if you can come up with a work-around for this, but I do prefer having this feature enabled, as I use Edge as my daily driver and the quicker launch times are noticeable.
Thanks for listening.