<script>
!function(n){
var e = n.document,
t=e.documentElement,
i=750,
d=i/100,
o="orientationchange"in n?"orientationchange":"resize",
a=function(){
var n=t.clientWidth||320;n>720&&(n=720);
t.style.fontSize=n/d+"px"
};
e.addEventListener&&(n.addEventListener(o,a,!1),e.addEventListener("DOMContentLoaded",a,!1))
}(window);
</ script>
to this code, placed html page, such as the total width of 750px design draft, a <div> element 600px wide, then css is: div {width: 6rem}
to this code, placed html page, such as the total width of 750px design draft, a <div> element 600px wide, then css is: div {width: 6rem}