Post Grid Styling not working

I tried the shortcode which was explained here: https://displayposts.com/2019/01/04/post-grid-styling/
I also added the custom CSS.
But my posts don’t get displayed as they should.
I see this: https://www.evernote.com/l/AtXTVW7N2r9DaKHsBA-YQno5Xhakzi4kWUM/
(My page is not online yet so can’t share the actual page)
Strange thing is, when I’m editing it does seem fine, but as soon as I publish it’s not okay.
The problem seems to be with the part that refers to the custom CSS, because all other shortcodes do work.

The page I need help with: [log in to see the link]