// 计算根节点1rem的值
(function(doc, win) {
  let docEl = doc.documentElement
  // recalF,
  let resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize'
  let recalc = function() {
    var clientWidth = docEl.clientWidth
    if (!clientWidth) return
    // 按照效果图尺寸及方便计算的规则，确认1rem基本字号大小。此处为1rem=10px
    docEl.style.fontSize = parseInt(10 * (clientWidth / 1024)) + 'px'
  }
  if (!doc.addEventListener) return
  win.addEventListener(resizeEvt, recalc, false)
  doc.addEventListener('DOMContentLoaded', recalc, false)
})(document, window)