body {
    font-family: Arial,Helvetica,sans-serif;;
    background-color: white;
    background-image:url('imagenes/ilumina0.jpg');
    background-size: 55%;
    background-repeat:no-repeat;
    background-position:center top;
    text-align: center;
    margin-top: 175px;
}


div#contenido {
    background: #DBE3EA;
    display: inline-block;
    font: Verdana 25px;
    width: 800px;
}

h1 {
    color: blue;
}

.imgder {
    width: 300px;
    border: 1px solid blue;
    padding: 1px
}