.section{
    width: 100%;
    height: 100vh;
    background-image: url(../images/lunamy.jpg);
    background-color: #2A3A47;
    background-size: 100%;
    background-repeat: no-repeat;
    background-position: center;
}

@media(max-width:700px){
    .section{
        width: 100%;
        height: 100vh;
        background-image: url(../images/movil.jpg);
        background-size: cover;
    }
}