What is the corner radius of the windows in Mac OS X? I kind of like to have stuff right on the dot and it'll bug me until I find out.
Nowadays it seems to be more like 5px.
The black around the window (I used a Finder.app window for that, to ensure that I have a native one) is the rim shadow from Mojave's dark mode which makes for a pretty good guideline for the orange border I placed.
I experimented with 4px and 6px, but 5px seems to hit the mark best.