html {

}
div#center {
    width: 95vw; /*fallback*/
    margin-left: auto;
    margin-right: auto;
    background-color: rgba(255, 255, 255, .8);
    margin-top: 10vw;
}
@media only screen and (max-width: 1200px) {
    html {
        font-size: 1.6vw;
    }
}
@media only screen and (min-width: 1200px) {
    div#center {
        width: 80vw;
    }
    html {
        font-size: 1.34vw;
    }
}
@media only screen and (min-width: 1600px) {
    div#center {
        width: 60vw;
    }
    html {
        font-size: 1vw;
    }
}