@media screen and (max-width:768px){
    html{
        font-size: 20px * (768 / 320);
    }
} 
@media screen and (max-width:480px){
    html{
        font-size: 20px * (480 / 320);
    }
}
@media screen and (max-width:375px){
    html{
        font-size: 20px * (375 / 320);
    }
}  
@media screen and (max-width:360px){
    html{
        font-size: 20px * (360 / 320);
    }
} 
@media screen and (max-width:320px){
    html{
        font-size: 20px * (320 / 320);
    }
} 
@media screen and (max-width:240px){
    html{
        font-size: 20px * (240 / 320);
    }
} 
@media screen and (max-width:176px){
    html{
        font-size: 20px * (176 / 320);
    }
}