div#centro {float:left; width:74%; text-align:left; margin:1ex 2.5% 0 2%;}

.contenido3 {background:#eef0f2; border:0; margin:0.1ex 0.2ex 0 0.2ex;}
.contenido3 a {color:#3E454D; text-decoration: none; display:block; padding:0.5ex;}
.contenido3 a:hover {background:#EBF8FB; color:#025988;}

.relac {background:#3E454D; color:#eef0f2; border:0; margin:0.1ex 0.2ex 0 0.2ex; padding:0.5ex;}