In order to implement WikimediaUI Base in WikimediaUI theme, we need to minimize differences between {rWMUI} `/wikimedia-ui-base.less` and the existing theme variables in common.less. (continuing work from @Prtksxna comment)
### `SAME` variable name
* `@color-placeholder`
* `@color-destructive`
* `@background-color-framed`
* `@background-color-destructive`
* `@background-color-tabs`
* `@box-shadow-dialog`
* `@box-shadow-toolbar*`
* `@box-shadow-widget`
* `@box-shadow-frameless-focus`
* ...some more shadow stuff...
### `VALUE` is slightly different
[x] `@background-color-destructive` fixed by https://gerrit.wikimedia.org/r/355433
### `MISTAKE` in rWMUI?
[x] Should `@background-color-primary` be `@wmui-color-accent90`?
Yes. Fixed in D660.
[x] Should `@color-primary--focus` be `@color-primary` instead of `@wmui-color-accent50`?
tl;dr Yes. I'm not having a strong conviction on what is the more insightful way for devs, but consistency is important so let's follow the OOjs UI way.
### `MISSING` variables
* Most size stuff
OOjs UI specifics, that we shouldn't put into WikimediaUI Base right now
* A bunch of font stuff
* `@oo-ui-font-size-browser` – debatable if we should generalize this
* `@oo-ui-font-size-default` – debatable if we should generalize this
* `@color-destructive-non-primary` – OOjs UI specific
* `@opacity-disabled-indicator`– OOjs UI specific
* `@opacity-disabled-tool` – debatable if we should generalize this
* `@border-radius-frameless` – debatable if we should generalize this
* `@border-width-medium` – removed, wasn't in use any more in connected patch