Replace obsolete LESS `box-shadow()` mixin
Replace obsolete LESS `box-shadow()` mixin

With unprefixed property.
Also reordering `color` properties directly after background* to align
with property order coding guidelines.

Change-Id: Ifbcd42080198da6239716ccc21c9486c166fd6c3

wikimedia/mediawiki-extensions-Graph,wikimedia/mediawiki-extensions-Graph