As a part of #2
http://www.irtcalendar.com/node/10278

You currently have a setup where you have three variations of color displayed for various purposes. The header a dark variant of a color, then the weekday header a medium variation of a color, and then the week highlight the lightest color variation (In the month view layout in the lower right month preview).

You also have a prefernce now in the Day view that allows you to switch to a Thin blue or Thin Dark header color theme.

For those who want to change their colors (I love blue by the way), You might want to setup a preference for Theme color and give them a few more options than Dark and Blue.