Add class to outer div in DotNetNuke containers

Container.ascx

<%@ Control language="c#" AutoEventWireup="true" Explicit="True" Inherits="DotNetNuke.UI.Containers.Container" %>
<%@ Register TagPrefix="dnn" TagName="TITLE" Src="~/Admin/Containers/Title.ascx" %>
<script runat="server">    
    protected void Page_PreRender(object sender, EventArgs e) {
        try {
            HtmlGenericControl cParent = (HtmlGenericControl) this.Parent;
            cParent.Attributes["class"] += " tab";
        } catch (Exception ex) { 
            // do nothing 
        }
    }
</script>
<div class="title">
	<h4>
		<dnn:TITLE runat="server" CssClass=" " />
	</h4>
</div>
<div runat="server" CssClass="content" id="ContentPane" />