Additional changes:
* Separate CSSCustomProperties.less from skin.less so that
we can obtain the unmodified original values for the colors
Depends-On: I363a97d33d85a9033da753f2a8fe730d80206639
Depends-On: I148eaca747352ffdc9d1423f20d34bd5a1d0e447
Bug: T356427
Change-Id: I916450c276cabb0c7c871525c50f95fb87f498ad
All colors used in Minerva are converted from Less variables
into CSS custom properties. A new file called CSSCustomProperties.less
is created in the skins.minerva.base.styles module to store
these custom properties and an ADR is provided on the rationale for
dropping support for browsers that don't support custom properties.
The new CSS custom properties follow Codex design token conventions
where possible (and noted when not).
Link colors are unique because their styles are defined in core,
so in that case the Less variables values are set to custom properties.
Those values are then fed back into MediaWiki core for core link
styling.
Also adds a temporary night-mode color palette under the
.skin-nightmode-1 class on the <html> element.
Bug: T356074
Change-Id: Ida1f14138f12bd3c600c264bde7b5100f9dbf4ff
Adds an ADR explaining the intent of use CSS custom properties for
night mode in Minerva.
Bug: T356074
Change-Id: I3a67f31ec426a3bb29e36c45adbcc0122e673d85
Adds the first ADR to the MinervaNeue skin.
The file is placed in a top-level `/adr` folder since the `/doc` folder
is already used for auto-generated documentation.
Change-Id: I83ad4a1bf8e81caaea9312d4c3efc3bf5ce419be
