<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>Document</title><style>.fu {position: relative;width: 400px;height: 400px;background-color: pink;}/* .fu div:first-child {position: absolute;top: 50%;left: 50%;transform: translate(-50%, -50%);width: 200px;height: 200px;background-color: purple;} */.fu div:first-of-type {position: absolute;top: 50%;left: 50%;transform: translate(-50%, -50%);width: 200px;height: 200px;background-color: purple;}</style>
</head><body><div class="fu"><div class="child"></div></div>
</body></html>
