Creating Transparent Text Box for All Post Titles

On the main page of my website, there is a transparent, grey text box between the article title “The Confidence Trick”, and the background image. But when you click it, and go to the post page, this transparent, grey box is no longer underneath the title. I would like this box to be under all the article titles of all my post pages. I am using the Tirpitz theme.

I have created a child theme using the childify me plugin, but I am new to wordpress, so I am unsure how to use the theme and have had trouble making changes using it.

Thanks for any help any of you can provide.