As regards marking a day as "chageoverday" (I imagine you mean
regardless of it's actuall booking state) could be done either via php
by modifying the code that puts the calendar together or by
javascript. Doing it in php would probably be a better solution.
If you look at the "ac-includes" > "functions.inc.php" flle you should
see some code that detects the weekend days and adds the class
"weekend" to them like this:
// add weekend class - used in javascript to alter class or set
opacity
if ($day_num % 7 == 1) $day_classes.=' weekend';
elseif ($day_num % 6 == 1) $day_classes.=' weekend';
You could copy those lines (you actually only need one of them) and
playaround with the numer (eg 5=saturday) and add an extra class to
the date such as "changeover".
Then, in the css, add this style and define it's border color or style
(don't use the background as this will be overwritten)
Let me know if you need anymore help with this .
Chris