Moving (mockup) TOC (Plone 5)

For my content type (book) I need to have the toc hidden, but showing when a 'toc-menu-button' is clicked.

As the toc is generated from mockup (?), it looks to me like I can not move it (to another div) with diazo.
Also, it does not seem doable with (just) CSS, as something is wrong with the z-indexes (The h1 and h2 titles always has higher zindex and shows 'on top of the toc'.

Is there a smart way to do this?