I have a wordpress website and i am using a content slider at the top of the page, i want to apply a background colour overlay to the images but im unsure of the code required and which class/id to apply it to

the code i have for the overlay is

background-color: rgba(255, 255, 255, 0.7);

I’ve added an ID to the main container which houses the slider (#slider) and tried applying the styling there but it doesn’t work

I’m trying to achieve a colour overlay with a reduced opacity to the slides to “darken the images” and allow the text to be read easier.

The website in question is www.sennencommunitycentre.co.uk and i’d really appreciate any assistance in solving this

Many Thanks