Header display issues (font color, background-size)
The defaults for header display could be improved. On a white or transparent background image, the default white text color on the default light theme makes the public name/short description very hard to read, especially if admin doesn't have or care to use a background image. Maybe a better default would be an outline vs a drop shadow, something like:
text-shadow: -1px -1px 1px #000, 1px -1px 1px #000, -1px 1px 1px #000, 1px 1px 1px #000;
Also, although the responsive design is generally quite good, background-size:contain might be better for the header than the default background-size:cover as the default cuts off many banner-type images that include text (and otherwise makes banner positioning unintuitive) even at the recommended 600x100 aspect ratio. I don't believe that is an advisable minimum size for background-size:cover.
Also regarding the responsive design in the header, the font size is not responsive and the text wraps poorly on mobile devices:
