.capa { position: absolute; left : 200px; top : 100px; width: 200px; height : 300px; background-color: white; display: none;}
function mostrar(capa) { document.getElementById("info"+capa).style.display="block";}
<select onchange="mostrar(1);"><option></option></select><div class="capa" id="info1">Información a mostrar.</div>
.clase { position: relative; left: -1px; top: -2px;}