.contact {
    display:flex;
    justify-content:center;
    margin-top:10%;
}

html {
    background-image: url(../img/fondo-hero.png);
}

#receivedMessage {
    margin-top:10%;
}

@media screen and (max-width: 900px) {

    .contact { 
        flex-direction:column;
        margin-top:20%;
    }

    .img-section img {
        width:90%;
        margin-top:30px;
    }

    #sendMessage {
        margin-left:30%;
    }
}