html, body, #a {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
	
	transition: background-color 3s cubic-bezier(1, 1, 1, 1);
	transition-delay: 0s;
}

#a {
    display: table;
}

#b {
    display: table-cell;
    margin: 0;
    padding: 0;

    text-align: center;
    vertical-align: middle;
}

#content {
    width: 200px;
    height: 200px;
    margin: auto;
}