fix: react-scripts build ParserError

Author: mrholek

scss/mixins/_grid.scss

@@ -7,9 +7,9 @@
   --#{$variable-prefix}gutter-y: 0;
   display: flex;
   flex-wrap: wrap;
-  margin-top: calc(var(--#{$variable-prefix}gutter-y) * -1); // stylelint-disable-line function-disallowed-list
-  margin-right: calc(var(--#{$variable-prefix}gutter-x) * -.5); // stylelint-disable-line function-disallowed-list
-  margin-left: calc(var(--#{$variable-prefix}gutter-x) * -.5); // stylelint-disable-line function-disallowed-list
+  margin-top: calc(-1 * var(--#{$variable-prefix}gutter-y)); // stylelint-disable-line function-disallowed-list
+  margin-right: calc(-.5 * var(--#{$variable-prefix}gutter-x)); // stylelint-disable-line function-disallowed-list
+  margin-left: calc(-.5 * var(--#{$variable-prefix}gutter-x)); // stylelint-disable-line function-disallowed-list
 }
 
 @mixin make-col-ready($gutter: $grid-gutter-width) {