WOW, I am very impressed with the results of your latest build. It is quite an improvemnt in my opinion. And I am imrpessed how quickly you did all that programming.
Having the Today color be the background color is a much better idea than colorizing the header. Great idea!
I have a couple of quick comments.
1) Since there seems to be a lot of room, you might want to increase the notation from DY to Day in the header, but I do understand your doing a 2 charecter format. You may also want to do Week instead of WK. It just makes it nicer when things are spelled out when you have the room. But I love it as is too and am fine with it. Great job
2) The Header style preference is great. I am keeping mine on the Thin blue so it matches the Week and Month themes. You might want to break this up into 2 parts. One for the format style and how it is applied to the Day view. And Two, the e.g. thin blue or dark becomes a Header theme that can be applied to each layout in the program. e.g. Day, week or Month. Maybe in the future you may come up with more styles and it can be added there.
3) I like them on, but since you have a toggle for the Day #, you may want to add a toggle for Week # as well?
I really love what you did with this release. You did a very good job. It really looks nice. I look forward to your continued hard work.