How can I make a text box transluscent so I can see the background through it?

Good Evening!

I am using the Wordpress Page builder with the Diva Theme. With the page builder, I have chosen to use a Call to Action Module which uses a background to create a highlight for the text box. I would like to have these particular textboxes to be translucent so my webpage background can still be seen through as people scroll through the texts.

I want to do this on all my pages of my website.
Any help you can give me would be most appreciated.
Thank you,
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