Created by: pat270
This pull removes the &:not(:disabled):not(.disabled) selector on the .close component and styles :disabled/.disabled directly because the :not pseudo classes are too hard to overwrite (breaks for people that extended .close based on the old version).
Also added variables:
$close-opacity
$close-hover-color
$close-hover-opacity
$close-disabled-opacity
Fixes #27784 (closed)