Adding static image to Sugarcube 2.11.0

Before anyone shouts, I've looked through the docs and can't find the answer.

I wanted to add it to the dynamic 'slidy' sidebar in place of the title, but had no joy.

I can get it to appear in a passage with:

[img[title_picture.jpg]]

But I don't want to have to insert that in every passage.

I also tried:

.passage {background-image: url("title_picture.jpg");}

In the CSS, but again no joy.

And yes, I am publishing to file before I check to see if it's worked.

Any way to get it as a static image that sits above the passage descriptions without using the macro in every passage?