fix release new sass variables: lms/static/sass/base/_variables.scss

copied over from kluo/bulk-email-squashed work,

lms/static/sass/base/_variables.scss

@@ -44,6 +44,11 @@ $dark-gray: #333;
 // used by descriptor css
 $lightGrey: #edf1f5;
 $darkGrey: #8891a1;
+$blue-d1: shade($blue,20%);
+$blue-d2: shade($blue,40%);
+$blue-d4: shade($blue,80%);
+$shadow: rgba($black, 0.2);
+$shadow-l1: rgba($black, 0.1);
 
 // edx.org-related
 $m-gray-l1: rgb(203,203,203);