[designfix] use sprites for top navigation images

public/stylesheets/application.css

@@ -1203,14 +1203,22 @@ a:hover {
   width:100%;
 }
 #header li.drop-down > a {
-	background:url(../images/arrow-down-white.png) no-repeat right center;
+  /* Arrow down white */
+  background-image:url(../images/top_menu_arrow_grey_white_sprite.png);
+  background-position:right -40px;
+  background-repeat:no-repeat;
 	padding-right:35px;
 }
 #header li > a:hover {
         background-color:#700407;
 }
 #header li.drop-down > a:hover {
-        background:#700407 url(../images/arrow-down-grey.png) no-repeat right center;
+  /* Arrow down grey */
+  background-image:url(../images/top_menu_arrow_grey_white_sprite.png);
+  background-position:right -2px;
+  background-repeat:no-repeat;
+
+  background-color:#700407;
 	padding-right:35px;
 }
 #header li li a:hover {
@@ -1245,10 +1253,15 @@ li a.help {
   text-indent:-999em;
   width:20px;
   height:43px;
-  background:url(../images/icon_help.png) no-repeat 50% 50%;
+
+  /* Question mark white */
+  background-image:url(../images/question_mark_grey_white_sprite.png);
+  background-repeat:no-repeat;
+  background-position:center -6px;
 }
 li a.help:hover {
-  background-image:url(../images/icon_help_grey.png);
+  /* Question mark grey */
+  background-position:center -41px;
 }
 #header li.drop-down.open > a {
 	background:#FFFFFF url(../images/arrow-down-grey.png) no-repeat right center;