I want to add a horizontal line as a spacer between two elements.

I have a working solution based on prince discarding margins, but that works only with forced breaks.

How can I do that with breaks that prince adds?

See attachment for example rendering.

1. spacer.png‎ 61.5 kB

There isn't a CSS mechanism for controlling appearance based on page breaks like this, so I think at the moment it will require a multi-pass mechanism using JavaScript to scan the converted document and identify spacers that appear at the top of a page and change their style to be invisible.