// Png-fix
  $(document).ready(function(){$(document).pngFix();});
  // Image-preloader function 
  $.preload = function(){jQuery.each (arguments,function (e) {jQuery("<img>").attr("src", this);});}
  
  $(document).ready(function()
    {
      // Top buttons hover
      $.preload("/img/login_a.png", "/img/logout_a.png");
      $(".login_button").mouseover(function(){$(".login_button").css("background-image", "url('/img/login_a.png')");});     
      $(".login_button").mouseout(function(){$(".login_button").css("background-image", "url('/img/login.png')");});
        
      $(".logout_button").mouseover(function(){$(".logout_button").css("background-image", "url('/img/logout_a.png')");});     
      $(".logout_button").mouseout(function(){$(".logout_button").css("background-image", "url('/img/logout.png')");}); 
    });