Remove shadow below HeaderBar for content apps
AdwToolbarView (technically the revealer), has a box-shadow over the content below the HeaderBar. I noticed that because I was wondering if something is wrong with the image I'm viewing or if that's just an intentional adwaita effect.
In my opinion, the app should interfere as little as possible with content like images or videos. I also think it's more problematic than rounded window corners because it's hard to tell which amount of darkening of the image comes from the app or if it comes from the app at all.
My idea would be to use a 1px border instead of the shadow for media apps (image, video).