I'm not very happy with it, but here's something that seems to work in ADE.
It uses tables (ugh), and the behaviour isn't consistent across renderers. Or even terribly logical. But it's the best I can come up with, since ePub CSS doesn't support the position: attribute. The easiest way to adjust the positioning of the lines is to tweak the graphic. No doubt there's other ways too, to do with vertical alignment in table cells.
It might be possible to do something better with an SVG graphic for the entire heading - I haven't looked.
Originally Posted by ghostyjack
Any joy on the getting the image files to stretch across the page after the title (my question 2)?