#contenido
{
    position: relative;
    float:left;
    width: 35em;
    height: 30em;
}
#desarrollofondo
{
    position: relative;
    float: right;
    width: 25em;
    height: 17em;
    background-image: url(../images/investigacion-esclerosis-parkinson.jpg);
    background-repeat: no-repeat;
    background-position: right;
}