Ability to add special class to first and last day of reservation in calendar

I would like to add a special class to the first and last day of the reservation in the calendar.
I have already found that I should edit /libraries/solidres/utilities/calendar.php, but how can I edit it to add that special class to only the first and last day of a reservation?
The main goal is to achieve an effect like you can see on the attached image.

Hi,

This feature will be implemented in the next release.

Cheers,

Hi solidres,

when will the next release be available? Any specific date scheduled yet?

Thanks,
Stefan

Hi,

Nice week to you.

It should be released within this month.

Regards,