addressing UX/FED feedback:

* aligment of optional problem-centric feedback field's label
* visual vertical spacing of criterion-specific comment
* visual vertical spacing of 'Additional Comments' UI elements in grade report

apps/openassessment/xblock/static/sass/oa/utilities/_extends.scss

@@ -159,7 +159,7 @@
 // rubric question
 %ui-rubric-question {
   @include clearfix();
-  margin-bottom: ($baseline-v/2);
+  margin-bottom: ($baseline-v*2);
   @extend %wipe-last-child;
 
   .question__title {
@@ -183,7 +183,7 @@
 %ui-rubric-answers {
   margin-top: $baseline-v;
   margin-bottom: $baseline-v;
-  margin-left: ($baseline-h/4);
+  margin-left: ($baseline-h/2);
 
   .answer, .answer--feedback {
     @include row();
@@ -327,7 +327,6 @@
 
   // ELEM: open text feedback for answer
   .answer--feedback {
-    margin-top: ($baseline-v);
 
     .answer__label {
       margin-bottom: ($baseline-v/4);

apps/openassessment/xblock/static/sass/oa/views/_oa-base.scss

@@ -631,6 +631,10 @@
           margin-top: $baseline-v;
         }
 
+        .question__title__copy {
+          margin-left: 0;
+        }
+
         textarea {
           @extend %ui-content-longanswer;
           min-height: ($baseline-v*5);
@@ -990,7 +994,7 @@
     }
 
     .answer--feedback__content {
-      margin-top: ($baseline-v);
+      margin-top: ($baseline-v/4);
     }
 
     .feedback {