html,body{
	height: 100%;
	width: 100%;
        background-color: #000000;
        background: url(sfondo.jpg) no-repeat center center fixed;
        background-size: cover;
	margin:0 auto;
	overflow: hidden;
	}

#barra_top{
	height: 120px;
  	width: 100%;
  	position: absolute;
	background: #000000;
	}

#barra_bottom{
	height: 60px;
  	width: 100%;
  	position: absolute;
	bottom: 0px;
	background: #000000;
	}