body {
    background: url('../img/fondo.jpg') no-repeat center center;
    background-size: cover;
}

.main {
    margin-top: 100px;
}

[class*="col-"] {
    display: inline-block;
}

.fila {
    text-align: center;
    margin-bottom: 42px;
}

.col-6 {
    width: 49%;
}

.col-12 {
    width: 100%;
}

@media only screen and (max-width: 1024px) {
    /* For mobile phones: */
    [class*="col-"] {
        width: 100%;
        margin-bottom: 120px
    }
}