.haveInput{width: 100px;height: 100px;background: red;}
/*输入后删除该class*/
.haveInput:before {content: attr(placeholder);display: block;color: #333;}
<div placeholder=‘请输入‘ class="haveInput" contentEditable=‘true‘></div>
原文：https://www.cnblogs.com/caoruichun/p/10753946.html