html {
    font-size: 20px;
}

@media only screen and (min-width:400px) {
    html {
        font-size: 20px !important;
    }
}

@media only screen and (min-width:414px) {
    html {
        font-size: 20px !important;
    }
}

@media only screen and (min-width:480px) {
    html {
        font-size: 20px !important;
    }
}