html {font-size:10px}
 
@media screen and (min-width:480px) and (max-width:639px) {
    html {
        font-size: 15px
    }
}
 
@media screen and (min-width:640px) and (max-width:719px) {
    html {
        font-size: 20px
    }
}
 
@media screen and (min-width:720px) and (max-width:749px) {
    html {
        font-size: 22.5px
    }
}
 
@media screen and (min-width:750px) and (max-width:799px) {
    html {
        font-size: 23.5px
    }
}
 
@media screen and (min-width:800px) and (max-width:959px) {
    html {
        font-size: 25px
    }
}
 
@media screen and (min-width:960px) and (max-width:1079px) {
    html {
        font-size: 30px
    }
}
 
@media screen and (min-width:1080px) {
    html {
        font-size: 32px
    }
}