MDL-79863 qtype_ordering: Made with of draggable fields relative

I found out that together with the plugin active quiz, the fixed with
to 360 px leads to problems when viewed responsive in smaller mobile
devices like smartphones. So I changed the with to a relative value of
80%.

question/type/ordering/styles.css

@@ -7,7 +7,7 @@
     margin           : 0px;
     margin-left      : 5px;
     padding          : 4px 4px 0 4px;
-    width            : 360px;
+    width            : 80%;
 }
 .que.ordering ul.sortablelist li {
     background-color : #eeeeee;