body { background:#FF0; }

#page-wrap { width: 700px; }
#page-wrap:after { content: "Pantalla Mediana"; }
#main-content { float: right; width: 440px; height: 300px; }
#secondary-one { float: left; width: 170px; height: 300px; }
#secondary-two { display: none; }
#detalle { width: 440px; height: 250px; position:relative}