min height on droppable areas and add padding to top/bottom on hover.

cms/static/js/base.js

@@ -112,12 +112,14 @@ $(document).ready(function() {
     	accept : '.unit',
     	greedy: true,
     	tolerance: "pointer",
+    	hoverClass: "dropover",
     	drop: onUnitReordered
     });
     $('.subsection-list > ol').droppable({
     	// why don't we have a more useful class for subsections than id-holder?
     	accept : '.id-holder', // '.unit, .id-holder',
     	tolerance: "pointer",
+    	hoverClass: "dropover",
     	drop: onSubsectionReordered,
     	greedy: true
     });

cms/static/sass/_courseware.scss

@@ -643,4 +643,12 @@ input.courseware-unit-search-input {
 	margin-top: 10px;
 	font-size: 13px;
 	color: $darkGrey;
+}
+
+.ui-droppable {
+    min-height: 22px;
+    &.dropover {
+        padding-top: 11px;
+        padding-bottom: 11px;
+    }
 }