fix css typos
Merge pull request #194 from christianwach/cmw-fixes

Fix -webkit prefix typos in CSS.

Props @christianwach.
Fix footer overlay.

When rendering an Infinity overlay option, set an additional CSS rule so
`display:block` applies to the :before pseudo element.

This ensures that overlays are applied correctly.

Fixes #182.
Remove invalid CSS selector when setting the Groups widget icon.

This led to the character "f" replacing the entire Groups widget in
Opera v12.

RIP Opera Presto.  We'll miss you.

Fixes #162.
Port over latest bp-default strings to cbox-theme.

Props @btalberg.

Fixes #189.