//h5的设计图一般都是750或者345,640，

(function(win, doc) {
if (!win.addEventListener) return;
var html = document.documentElement;

function setFont() {
var html = document.documentElement;
var k = 750;//设计图大小
html.style.fontSize = html.clientWidth / k * 100 + "px";
}
setFont();
setTimeout(function() {
setFont();
}, 300);
doc.addEventListener('DOMContentLoaded', setFont, false);
win.addEventListener('resize', setFont, false);
win.addEventListener('load', setFont, false);
})(window, document);