em px 谷歌浏览器默认font-size 2021-07-2

谷歌浏览器默认font-size 16px

class 3 = class 2 class width = font-size * em class height = font-size * em

<div class="1" style="font-size: 100px;height: 60px; width: 60px; border: 1px solid red" ></div>
    <div class="2"  style="font-size: 16px; width: .6em; height: .6em; border: 1px solid red"></div>
    <div class="3"  style="width: .6em; height: .6em; border: 1px solid red"></div>