Not lot of documentation BUT you can check out @gf_wolfer’s Top Shelf Elements
If you poke around on that page you’ll notice that he also has a pretty sick plug-in but it doesn’t come with a calendar that you can customize although you can use it to make your own calendars very easily.
The page I shared doesn’t use any plug-ins created by him OR me. Instead it uses a free Plugin Called toolbox to create calendar dates. You could easily adapt to this and create a very customized sweet looking calendar.
If you’re looking for something with a Full Calendar features and flexibility with customization on how it looks, my full calendar Plugin can use all bubble control buttons instead of the standard FullCalendar buttons. I didn’t like how it looks out of the box either and opted to be able to remove the default Calendar header and replace it with your own buttons. My calendar Plugin is also now coming with a new date and time picker that looks very nice on mobile and has a dark appearance on desktop or laptop
Honestly with just some tedious work. you can use custom css to overwrite the old designs and create your own look.
That’s what I did with my plugin to make it look a little nicer.