//头部、底部加载
(function (win) {
      resizeroot();
      function resizeroot() {
          var wwidth = document.documentelement.clientwidth;
          if (wwidth > 640) wwidth = 640;
          else if (wwidth <320) wwidth = 320;
          document.documentelement.style.fontsize = wwidth / 39 + 'px';
      }
      window.onresize = resizeroot;
})(window);