.header { max-width: 960px }
.slider { max-width: 920px; }
.mainContent { max-width: 960px }
.footer { max-width: 960px }
@media only screen 
and (max-width : 1319px) {
	.mainContent {
		margin: 0 auto;
		display: block;
	}
	.footer {
		margin: 0 auto;
		display: block;
	}
}