Updated all the places in the SCSS where we use Darken and Lighten properties.
These properties have been problematic in the past and caused some state issues, e.g. New message(s) hightlight (which was fixed seperately from this issue)
Updates maintain WWW color variable naming conventions, but replaces values with 3.0 colors.
Colors have the commented HEX and GUI variable name.
More work to do auditing but it’s a start.
These warnings were annoying me because the noise makes it easy to miss real issues.
The `no-mergeable-selectors` rule is one that we do want to have, but right now it asks that you merge selectors in different `@media` blocks. When the next release happens we should put that back.
https://github.com/sasstools/sass-lint/issues/307
Similarly, we want `force-element-nesting` but there is a problem with that because there's no easy way to have a nested selector in a list of selectors.
https://github.com/sasstools/sass-lint/issues/575
Finally, until they implement per-line overrides, we have to silence `class-name-format` because we don't have control over the ReactModal class names. It's a useful rule to keep class names consistent though. Per-line ignores should be coming soon: https://github.com/sasstools/sass-lint/issues/70
