var bgNum = Math.round(Math.random() * 5)
  bgSel = new Array(6);
  
  bgSel[0] = "<style type='text/css'>body{background-repeat:no-repeat; background-position:center bottom; background-image:url(imagens/fundo03.jpg);}</style>";
  bgSel[1] = "";
  bgSel[2] = "<style type='text/css'>body{background-repeat:no-repeat; background-position:center top; background-image:url(imagens/fundo02.jpg);}</style>";
  bgSel[3] = "<style type='text/css'>body{background-repeat:no-repeat; background-position:center top; background-image:url(imagens/fundo01.jpg);}</style>";
  bgSel[4] = "<style type='text/css'>body{background-repeat:no-repeat; background-position:center top; background-image:url(imagens/fundo04.jpg);}</style>";
  bgSel[5] = "<style type='text/css'>body{background-repeat:no-repeat; background-position:center top; background-image:url(imagens/fundo05.jpg);}</style>";

  
  var bk = bgSel[bgNum];