function mouseover()
   {

       document.getElementById('li1').className="landscapes1";   
   }
   function mouseout()
   {
      document.getElementById('li1').className="landscapes"; 
   }
       function mouseover1()
   {
       document.getElementById('li2').className="people1";   
   }
   function mouseout1()
   {
      document.getElementById('li2').className="people"; 
   }
   function mouseover2()
   {
       document.getElementById('li3').className="nature1";   
   }
   function mouseout2()
   {
      document.getElementById('li3').className="nature"; 
   }