Fix issue causing .navbar-brand element height to be shorter than .navbar height
use correct+newer name for retina mixin in docs; fixes #12450
fix "pading-right" [sic] typo in dashboard.css; fixes #12455
Downgrade holder.js to v2.2.0.

Fixes #12440.
Merge pull request #12463 from XhmikosR/12440

Downgrade holder.js to v2.2.0.
fix #12484
Use scss option instead of css for better highlighting
Merge pull request #12448 from PHLAK/master

Fix issue causing .navbar-brand element height to be shorter than .navbar height
grunt after last commits