JSFiddle - React, Tailwind, and code Playground

HTML

<div>
  center
</div>

CSS

div{
    background: red;
    width: 100px;
    height: 100px;
    position: absolute;
    left: 50%;
    top: 50%;
    margin-top: -50px;    /* 高度的一半 */
    margin-left: -50px;    /* 宽度的一半 */
}