(function flexible(window, document) {
  var docel = document.documentelement
  var dpr = window.devicepixelratio || 1

  // adjust body font size
  function setbodyfontsize() {
    if (document.body) {
      document.body.style.fontsize = (12 * dpr) + 'px'
    }
    else {
      document.addeventlistener('domcontentloaded', setbodyfontsize)
    }
  }
  setbodyfontsize();

  // set 1rem = viewwidth / 10
  function setremunit() {
    var rem = docel.clientwidth / 10
    docel.style.fontsize = rem + 'px'
  }

  setremunit()

  // reset rem unit on page resize
  window.addeventlistener('resize', setremunit)
  window.addeventlistener('pageshow', function (e) {
    if (e.persisted) {
      setremunit()
    }
  })

  // detect 0.5px supports
  if (dpr >= 2) {
    var fakebody = document.createelement('body')
    var testelement = document.createelement('div')
    testelement.style.border = '.5px solid transparent'
    fakebody.appendchild(testelement)
    docel.appendchild(fakebody)
    if (testelement.offsetheight === 1) {
      docel.classlist.add('hairlines')
    }
    docel.removechild(fakebody)
  }
}(window, document))