The easiest way to do this is to make the text a child of the div
with the background image. The change to min-size is so that if
the text wraps often enough on narrow screens, the header expands
vertically rather than the text spilling over.
Fixes#3259
This fixes a glitch highlighted in #3259, where the css class stopped applying
when the view was moved to a different controller.
We're moving to having each view responsible for their layout, and commonly having
override classes explicitly in the relevant views. So we can follow that pattern here.
Since flash objects can only be String, Hash or Array (notably excluding SafeBuffers), then this approach is necessary to render complex html in a safe manner.
Each local can be treated as an (unsafe) string, and therefore escaped normally when rendered into the template. The template (and translation strings) can
contain html since they are no longer stored in the flash as a plain string.
Fixes#3215
