function About_on()
    {
        document.getElementById("About_Nav").src="images/about_on.jpg";
    }
    function About_off()
    {
        document.getElementById("About_Nav").src="images/about_off.jpg";
    }
    
    function Contact_on()
    {
        document.getElementById("Contact_Nav").src="images/contact_on.jpg";
    }
    function Contact_off()
    {
        document.getElementById("Contact_Nav").src="images/contact_off.jpg";
    }
    
    function Services_on()
    {
        document.getElementById("Services_Nav").src="images/left_services_on.jpg";
    }
    function Services_off()
    {
        document.getElementById("Services_Nav").src="images/left_services_off.jpg";
    }
       
    function CB_on()
    {
        document.getElementById("CB_Nav").src="images/cb_on.jpg";
    }
    function CB_off()
    {
        document.getElementById("CB_Nav").src="images/cb_off.jpg";
    }
    
    function TMB_on()
    {
        document.getElementById("TMB_Nav").src="images/tb_on.jpg";
    }
    function TMB_off()
    {
        document.getElementById("TMB_Nav").src="images/tb_off.jpg";
    }
    
    function DNS_on()
    {
        document.getElementById("DNS_Nav").src="images/dns_on.jpg";
    }
    function DNS_off()
    {
        document.getElementById("DNS_Nav").src="images/dns_off.jpg";
    }