Give them a min-height so that accessing their contextual links
is possible despite their initial lack of content.

The special-case styling of the cover-everything a tag in the header
changed the element flow and z-index, so the visualization icon was
behind the header and even all the way to the left, behind the
footnote title. Solution: Change a markup so that the title isn't
within it when rendering the teaser, and fix up styling.

This margin puts space between the supplemental files table (if any)
and the "Last updated on..." message.