bug#2812:forge主页、course主页搜索建议做成下拉按钮的样式

app/views/welcome/_search_project.html.erb

@@ -34,6 +34,9 @@ form #search_type{
 	-moz-appearance: none;
 	text-indent: 0.01px;
 	text-overflow: '';
+  padding-right:10px;
+  background-image:url(/images/arrow_expanded.png)!important;
+  background:no-repeat right;
 }
 
 form #search_by
@@ -68,6 +71,21 @@ form #search_by
 }
 <%#完了把上面东西放到 .css 里%>
 </style>
+<!--[if IE]>
+<!--<style type="text/css">-->
+  <!--form #search_type{-->
+    <!--background:none!important;-->
+  <!--}-->
+<!--</style>-->
+<![endif]-->
+<script type="text/javascript">
+  $(function(){
+    var userAgent = navigator.userAgent.toLowerCase();
+    if(/trident/.test(userAgent)){
+      $('form #search_type').css({'background-image':'none!important'});
+    }
+  });
+</script>
 <script type="text/javascript">
   function searchTypeChange()
   {