Fix scss import.

Author: crijke

src/styles/_theme.scss

@@ -1,7 +1,7 @@
 @import 'node_modules/carbon-components/scss/globals/scss/functions';
 @import 'node_modules/carbon-components/scss/globals/scss/mixins';
 @import 'node_modules/carbon-components/scss/globals/scss/typography';
-@import 'node_modules/carbon-components/scss/globals/grid/classic/classic';
+@import 'node_modules/carbon-components/scss/globals/grid/_classic';
 
 // Color Variables
 $green: #266050;