merged with current master

app/assets/javascripts/error_templates.js

@@ -0,0 +1,18 @@
+$(function() {
+    if ($.isController('error_templates')) {
+        $('#add-attribute').find('button').on('click', function () {
+            $.ajax(location + '/attribute.json', {
+                method: 'POST',
+                data: {
+                    _method: 'PUT',
+                    dataType: 'json',
+                    error_template_attribute_id: $('#add-attribute').find('select').val()
+                }
+            }).success(function () {
+                location.reload();
+            }).error(function (error) {
+                $.flash.danger({text: error.statusText});
+            });
+        });
+    }
+});

app/assets/stylesheets/error_templates.scss

@@ -0,0 +1,9 @@
+#add-attribute {
+  display: flex;
+  max-width: 400px;
+  margin-top: 30px;
+
+  button {
+    margin-left: 10px;
+  }
+}

app/assets/stylesheets/exercises.css.scss

@@ -93,4 +93,16 @@ a.file-heading {
   margin: -1px 0 0 0;
   top: 100%;
   left: 0;
-}
+}
+
+.feedback {
+  .text {
+    margin-bottom: 10px;
+  }
+  .difficulty {
+    font-weight: bold;
+  }
+  .worktime {
+    font-weight: bold;
+  }
+}