Content using `header` as a CSS class was affected by skin styles
in Minerva being insufficiently specific to the skin‑specific elements.
This changes Minerva to use `class="minerva‑header"`, thus avoiding
the conflict and matching what Vector does.
Bug: T172626
Change-Id: Id8fbe61b2d1d4a89ec11ddfdf7837be797b3bd20
This could be made even simpler by not using a LESS varialbe for
hacks.less, but loading it conditionally through the moduel def.
But, as a first step we can merge the two as-is.
Given that the subject and target are always referenced together
in page views, there is no need to keep an alias around. However,
I'm keeping it anyway so as to not produce any
`/* {"skins.foo":"missing"} */` appendix to the stylesheet response
for these cached URLs.
Bug: T266361
Change-Id: I8578faab8ca32bd49be90711cbd5e182763b8065