1 ;(function flexible (window, document) {
 2         var docEl = document.documentElement
 3         var dpr = window.devicePixelRatio || 1
 4 
 5         // adjust body font size
 6         function setBodyFontSize () {
 7             if (document.body) {
 8                 document.body.style.fontSize = (12 * dpr) + ‘px‘
 9             }
10             else {
11                 document.addEventListener(‘DOMContentLoaded‘, setBodyFontSize)
12             }
13         }
14         setBodyFontSize();
15 
16         // set 1rem = viewWidth / 10
17         function setRemUnit () {
18             var rem = docEl.clientWidth / 10
19             docEl.style.fontSize = rem + ‘px‘
20         }
21 
22         setRemUnit()
23 
24         // reset rem unit on page resize
25         window.addEventListener(‘resize‘, setRemUnit)
26         window.addEventListener(‘pageshow‘, function (e) {
27             if (e.persisted) {
28                 setRemUnit()
29             }
30         })
31 
32         // detect 0.5px supports
33         if (dpr >= 2) {
34             var fakeBody = document.createElement(‘body‘)
35             var testElement = document.createElement(‘div‘)
36             testElement.style.border = ‘.5px solid transparent‘
37             fakeBody.appendChild(testElement)
38             docEl.appendChild(fakeBody)
39             if (testElement.offsetHeight === 1) {
40                 docEl.classList.add(‘hairlines‘)
41             }
42             docEl.removeChild(fakeBody)
43         }
44     }(window, document));