移动端适配

var refreshRem=(function refreshRem(){
    var deviceWidth=document.documentElement.clientWidth;
    deviceWidth=Math.max(Math.min(420,deviceWidth),320);
    document.getElementsByTagName('html')[0].style.fontSize=(deviceWidth/750)*100+'px';
    return refreshRem;
})();
var resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
window.addEventListener(resizeEvt,refreshRem,false);

@function rem($px){
  @return $px / 100 + rem;
}