CSS自适应布局

目标效果：

缩小浏览器之后

在<head>最前面引入flexible.js

<head>
 。。。
<script type="text/javascript" src="./lib/flexible.js"></script>
。。

</head>


flexible.js 内容如下

(function flexible (window, document) {
    var docEl = document.documentElement
    var dpr = window.devicePixelRatio || 1
    // adjust body font size
    // console.log(dpr)
    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))


然后根据当前浏览器宽度: 2048px = 10rem 推导出204.8px = 1rem 。对所有标签宽高，字体用到px的地方，换算成rem即可

> screen.width
< 2048