body {
	background: transparent url('http://cdn.backgroundhost.com/backgrounds/subtlepatterns/dirty_old_shirt.png') repeat;
}

.artigo {
	z-index: 2;
	display: block;
	positioN: relative;
	box-shadow: 1px 2px 5px 0 rgba(0, 0, 0, 0.16), 0 2px 10px 0 rgba(0, 0, 0, 0.12);
	margin: 0 auto;
	background-color: #fff;
	opacity: 0.9;
}

.margin-bottom-xs {margin-bottom: 2em;}  
.margin-bottom-sm {margin-bottom: 2em;} 
.margin-bottom-md {margin-bottom: 2em;}
.margin-bottom-lg {margin-bottom: 2em;} 

footer {
	color: #fff;
	padding: 10px;
}

img {
 max-width:100%;
}

iframe {
 max-width:100%;
}