Solved blog background image

Hello, how can I insert a background image in the blog article with css and make it independent of category / and the blog page itself?

In the attached images is the example:
img1 = Page of the entries with the list and the background Ok
img2 = Category page / News and background Ok
img3 = Article page and here is the problem
img4 = The same on smartphone and we see the background Ok

What I want is that in the case of the img3 the background is just above the related articles (blue section), like the rest of the design that I propose on the web.

The CSS I used is attached as well.
---
.free-archive-wrapper, .free-du-blog-1 {
background-size: contain;
background-position: bottom center;
background-image: url(https://copras.es/wp-content/uploads/2021/11/copras_tit_ppal.png),linear-gradient(180deg,#ffffff 0%,#bebebe 100%)!important;
background-repeat: no-repeat;
}
---
Thank you
All the best

 

Perfect, good idea.
In the attached image you can see the result.
I added a pixel on the top edge to visually separate the sections a bit.

Thanks a lot!