Issues with landscape logos and header containers

[Feng-Shui]

The current header layout has issues with SVG logo scaling.

When a large site name or slogan appears in the middle of the header, this can compress the logo container to the left and make the logo render very small. The solution to this was to add an inline style attribute that set a min-width on the logo's container

This was an ugly solution because a landscape logo may need to be bigger that the mobile viewport on desktop at which point the min-width rule caused the logo container to extend beyond the viewport.

I've attempted to resolve this using flexbox, PR to come.