Using a homepage slider, how can I put a background behind the text content?

.sppb-fullwidth-title,
.details {
    background: rgba(0, 0, 0, 0.2);
}

Sort of works but there's gaps between the title and text. Some sides I'm using title and text, some I'm using title, text and buttons.

This is the site we are rebuilding and want to replicate the background box on the slides:

Thanks!