.normas{
    margin-top: 0px;
    margin-right: auto;
    margin-left: auto;
    margin-bottom: 0px;
    background-image: url("imagenes/Normas legales1.png");
    width: 599px;
}
.encabezado{
    margin: auto;
    width: 90%;
    text-align: center;
}
.article{
    margin-top: 15px;
    margin-right: 15px;
    margin-left: 15px;
    margin-bottom: 15px;
    float: left;
    width: 30%;
	}

.imagen-flotante{
    display: none;
    position: relative; 
    width: 300px; 
    opacity: 1; 
    transition: opacity 3s; /* Transición de 3 segundos */ 
} 
.imagen-flotante img{
    width: 50%; 
    height: auto; 
    display: block;
} 
.imagen-flotante::before{
    content: ""; 
    position: absolute; 
    top: 0; 
    left: 0; 
    right: 0; 
    bottom: 0; 
    background-color: rgba(255, 255, 255, 0.5); 
    z-index: -1; 
    border-radius: 10px; 
}