Adding style for beta-label appearance in publisher formats
Make static Beta label visually consistent with others

Theres a version in FET, and the new GOV.UK component, but switching to
those is a more involved change and should be done later.

Manually tweaking makes this PR mergable
Fix beta-label grid/gutter alignment on mobile
Merge pull request #454 from alphagov/adding_style_for_beta_label

Adding style for beta-label appearance on publisher formats

The beta-label content needs to appear about the guide navigation so can't be nested within '.inner'. This style adds the left margin and a bottom margin.