body {
    /* If you want this on all pages, put it in 32mm.css.
       If only for contact, put it in contact.css and include that file only on contact.html. */
    background:
        linear-gradient(rgba(74,74,74,0.75), rgba(74,74,74,0.75)), /* Increased opacity for darker effect */
        url('../img/missionfundo.png') no-repeat center center;
    background-size: cover;
    min-height: 100vh;
}