.parallax {
    /* The image used */
    /*background-image: url('../img/parallax.jpg');*/

    /* Full height */
    height: 100%; 

    /* Create the parallax scrolling effect */
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}

.sombra{
    filter:brightness(0.4);
}