Update widget_search.htm

src/theme/dedebiz/widget_search.htm

@@ -2,7 +2,7 @@
     <form class="search" name="formsearch" action="{dede:global.cfg_phpurl/}/search.php">
         <input type="hidden" name="kwtype" value="0">
         <div class="input-group">
-            <input name="q" type="text" class="form-control" value="{dede:global name='keyword' function='RemoveXSS(@me)'/}" placeholder="请输入关键词">
+            <input name="q" type="text" class="form-control" value="{dede:global name='keyword' function='RemoveXSS(@me)'/}" placeholder="请输入关键词" required>
             <div class="input-group-append"><button type="submit" class="btn btn-success"><i class="fa fa-search"></i></button></div>
         </div>
     </form>