Background frame

Hi guys,
On the following page – https://casateulada.com/de/kalender-rates I’m trying to add a semi transparent black background to the images and the calendar, such as on the page https://casateulada.com/updated-calendar .
To do that, I added the following code to the Quick CSS box :

.page-id-2571 .avia-builder-el-3 { padding: 20px;
background-color: rgba(0,0,0,0.5); }

.page-id-2571 .avia-builder-el-6 { padding: 20px;
background-color: rgba(0,0,0,0.5); }

.page-id-2571 .avia-builder-el-9 { padding: 20px;
background-color: rgba(0,0,0,0.5); }

.page-id-2571 .avia-builder-el-12 { padding: 20px;

.page-id-2571 .avia-builder-el-15 { padding: 20px;
background-color: rgba(0,0,0,0.5); }

.page-id-2571 .avia-builder-el-18 { padding: 20px;
background-color: rgba(0,0,0,0.5); }

Yet, I don’t seem to get the black bagkround to wrap 2 out of 3 calendars and and the last photo of the property.
Can you help out?

Thank you.

Antonio