add visual indicator to revoke access 'buttons'

lms/static/sass/base/_variables.scss

@@ -29,6 +29,7 @@ $pink: rgb(182,37,104);
 $yellow: rgb(255, 252, 221);
 $red: rgb(178, 6, 16);
 $error-red: rgb(253, 87, 87);
+$danger-red: rgb(212, 64, 64);
 $light-gray: rgb(221, 221, 221);
 $dark-gray: rgb(51, 51, 51);
 $border-color: rgb(200, 200, 200);

lms/static/sass/course/instructor/_instructor_2.scss

@@ -64,7 +64,7 @@
       @include idashbutton(#eee);
 
       &.molly-guard {
-        @include idashbutton($red)
+        @include idashbutton($danger-red)
       }
     }
 
@@ -183,6 +183,12 @@
     margin-bottom: 1em;
   }
 
+  .revoke-link {
+    color: $danger-red;
+    text-decoration: underline;
+    cursor: pointer;
+  }
+
   .batch-enrollment {
     textarea {
       margin-top: 0.2em;