"admin/all.css" which imports these SCSS partials already imports the
color variables in "admin/variables", so actually there should be no
need to import the variables again.
However, "application.css" calls "require_tree", which means asset
precompilation through Sprockets would attempt to compile each of the
SCSS partials individually. When compiled individually, the color
variables are not available to these partials.
This is a quick solution to allow precompilation of "application.css" to
complete.
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