Replacing abandoned `@colorGray13` (`#ddd`) with
appropriate variable from WikimediaUI color palette and
remove unneeded `@chromeContentSeparator` var, which is
just used once and not in place with `.header` anyways.
Additional changes:
* Also aligning `border` values to each other.
Bug: T146799
Bug: T172850
Change-Id: Ia9a1736b1ea5fa080b4673038b2c23ddce90f135
This is programmatic output from python3 scripts/migrate.py
This will result in a Minerva skin dependent on MobileFrontend.
Post merge we will rename message keys to have minerva- prefix
Bug: T166748
Change-Id: Iff1f7e63e796cc5d4a6d2ab0370e0c33248d2fce