Add !default

packages/@uppy/core/src/_variables.scss

@@ -11,7 +11,7 @@ $color-green: #1bb240 !default;
 $color-orange: #f6a623 !default;
 $color-yellow: #ffd600 !default;
 $color-white: #fff !default;
-$color-lightgray: #eaeaea;
+$color-lightgray: #eaeaea !default;
 $color-almost-white: #fafafa !default;
 $color-cornflower-blue: #2275d7 !default;
 $color-asphalt-gray: #525252 !default;