body{
    	background-color:#000000;
		text-align:center;
    }
#myAlternativeContent{
		background-color:#000000;
		width:800px;
		margin-left:auto;
		margin-right:auto;
		text-align:left;
	}
IMG.centred {
        display: block;
        margin-left: auto;
        margin-right:auto;
    }