I want to show the first and last day of a calendar booking as a diagonal background, showing that property is actually available to book from the same day as the previous checkout with a diagonal background on the first and last child of the list.
Is it possible to create this effect I hacked together in photoshop?
Looking at your table of dates, I think the only way you can get this to work is to get the calendar to add classes to the shoulder days e.g. start-of-stay and end-of-stay. Then use Microthemer to create a selector for those days and apply the gradient above. You would reverse the colors for end-of-stay box.