Programmatic solution to change navigation id to highlight current page ASP.NET

public string PageSection { get; set; }

<%@ MasterType VirtualPath="~/foo.master" %>

Master.PageSection = "home";

<body ID="bodyTag" runat="server">

bodyTag.Attributes.Add("class", this.PageSection);

.home #homeNavItem,
.contact #contactNavItem
{
    color: #f00;
}

<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
  <siteMapNode>
    <siteMapNode url="~/Default.aspx" title="Home"  description="" />
    <siteMapNode url="~/Blog.aspx" title="Blog"  description="" />
    <siteMapNode url="~/AboutUs.aspx" title="AboutUs"  description="" />
  </siteMapNode>
</siteMap>

<asp:SiteMapDataSource ID="sitemapdata" runat="server" ShowStartingNode="false"  />
<ul id="navigation">
    <asp:Repeater runat="server" ID="navrepeater" DataSourceID="sitemapdata">
        <ItemTemplate>
            <li class="<%# SiteMap.CurrentNode.Equals(Container.DataItem) ? "activenav" : "inactivenav" %>"><a href="<%# DataBinder.Eval(Container.DataItem, "url") %>"><%# DataBinder.Eval(Container.DataItem, "title") %></a></li>
        </ItemTemplate>
    </asp:Repeater>
</ul>

<li id="homeNav">home</li>
<li id="blogNav">blog</li>

<body id="home">
<body id="blog">

#home #homeNav {background-image:url(homeNav-on.jpg);}
#blog #blogNav {background-image:url(blogNav-on.jpg);}

protected string _bodyId;

protected override void OnLoad(EventArgs e)
{
    _bodyId = "your css id name";
}

<body id="<%= _bodyId %>">