I am using the following code : \[code\] <%@ Master Language="C#" AutoEventWireup="true" CodeBehind="Site1.master.cs" Inherits="WebApplication3.Site1" %><!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"> <title></title> <link href="http://stackoverflow.com/questions/15627683/style.css" rel="stylesheet" /> <script type="text/javascript"> function change(color) { document.bgColor = color; } </script> <asp:ContentPlaceHolder ID="head" runat="server"> </asp:ContentPlaceHolder></head><body> <form id="form1" runat="server"> <p> </p> <div class="green"> <div id="slatenav"> <ul> <li><a href="http://stackoverflow.com/questions/15627683/WebForm3.aspx" id="green" onclick="change('green')">Home</a></li> <li><a href="http://stackoverflow.com/questions/15627683/WebForm4.aspx" id="red" onclick="change('red')">About Us</a></li> </ul> </div> </div> <div> <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server"> </asp:ContentPlaceHolder> </div> </form></body></html>\[/code\]Why it isn't working properly?