section form {
    max-width: 1000px;
    margin-left: auto;
    margin-right: auto;
}
section form .flex {
    margin-left: -7px;
    margin-right: -7px;
    -webkit-display: flex;
    display: flex;
    -webkit-justify-content: flex-start;
    justify-content: flex-start;
    -webkit-flex-wrap: wrap;
    flex-wrap: wrap;
}
section form .flex:before,
section form .flex:after {
    display: none;
}
section form .flex > div {
    padding-left: 7px;
    padding-right: 7px;
}
section form .flex-envio {
    margin-top: 10px;
}

section form .flex-envio .dua-checkbox label span {
    width: calc(100% - 18px);
}
section form .flex-envio .dua-checkbox label {
    -webkit-align-items: flex-start;
    align-items: flex-start;
}
section form .flex-envio .dua-checkbox input {
    margin-top: 3px;
}

@media (min-width: 768px) {
    section form .flex-envio > div + div > div{
        height: 100%;
        display: -webkit-flex;
        display: flex;
        -webkit-flex-direction: column; 
        flex-direction: column; 
        -webkit-justify-content: space-between;
        justify-content: space-between;
        -webkit-align-items: flex-end;
        align-items: flex-end;
    }
}
@media (min-width: 600px) {
    section form .btn-black {
        width: 220px;
    }
}