关于前端px转换成rem时数据尺寸不一致

想做一个屏幕尺寸为1920的适配但设置尺寸200 px 自动转换成2.5rem 但在浏览器上并不是200px 这是什么地方出问题了

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../js/flexible.js"></script>
    <style>
        @media screen and(max-width:1024px) {
            html {
                font-size: 42.66px !important;
            }
        }
        
        @media screen and(min-width:1920px) {
            html {
                font-size: 80px !important;
            }
        }
        
        .box1 {
            width: 2.5rem;
            height: 2.5rem;
            background-color: pink;
        }
        
        .box2 {
            width: 200px;
            height: 200px;
            background-color: plum;
        }
    </style>
</head>

<body>
    <div class="box1"></div>
    <div class="box2"></div>
</body>

</html>

//flxible.js
(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 / 24
        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))