Changing horizontal size of div

Hello all,

I am currently working on my first website and it’s coming along quite well. So far, I’ve managed to solve almost all my problems through these forums (they are a godsend) but there are a few things I can’t quite wrap my head around.

On my website, the date is shown with a yellow background and I’m not exactly sure how to make that yellow background -only- be behind the text. It’s a bit difficult to describe in words, so here is my website with an example of how I’d like it to be.

I’m quite a beginner, so please be forgiving with your explanations. And thank you in advance to anyone who replies.

My website
https://www.theparanormalunicorn.com/

The example
Note the white background behind the post-date
https://www.gottadancedirty.com/