body {
	margin-top: 50px;
	margin-bottom: 50px;
	background: none;
}

.full {
    background: url('img/background-sistema.jpg') no-repeat center center fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}