Hi Rolf,

We have a back-end View for this, if you check out the Calendar Page in WP-Admin.

The “Calendar” page is a user-friendly scheduler, it shows a reservation calendar with all scheduled appointments and events organized by employees, services, and locations. You can quickly find relevant data by using services, locations, and employee filters;

and it also shows which time slots are available in white - while the unavailable ones have this gray background color on them.

If you wish to change the background color for unavailable slots, for example set a red color, so it 'stands out more' from the free slots, at this time, we don't have a built-in user friendly option to edit colors for the back-end pages of Amelia, but we can add a suggestion for our developers - and they will do their best to add an option soon.

Please feel free to search through our feature suggestion page, 

 to see if someone may be already suggested this feature. If you can't see it, feel free to add your suggestion there, and as more people vote, the feature will move higher on the priority list.

You can certainly follow our changeLog page if you'd like, where we state any changes/new features/bug fixes during updates;

and our newsletter, so you're informed about new features, bug fixes, freebies, etc.

-

For the time being, I can only offer a custom solution, to change this color with custom CSS.

This hasn't been fully tested, but it works on my Test site, so you can try.

Here is the custom CSS I use :

#am-calendar .fc-nonbusiness {   
 background-color: #ff0b0b;
}

In order to add this to the WP back-end, I have installed this free plugin  Admin CSS MU,

and then I go to "Appearance/ Admin CSS MU" ,  and add the CSS, like this :

I change the colour to a random darker pink shade, just to see the difference, and it is certainly more noticeable :

So, if you wish, try this, and let me know if it works for you.

Please check out more details about the back-end Calendar view here.

Let us know if that helps and if you have any questions.