Dark UI Calendar.app
I felt like my visual design skill set was starting to atrophy so its time for some practice. I've wanted OS X to bundle a dark UI version of their stock apps to go along with the dark UI toggle for spotlight, the dock, and menu bar. I will probably do a finder window next.
Everything was 100% recreated, including the icons which in the past I've avoided doing.
Also, this was designed in Figma! Solid design tool based on this little exercise.