console 命令行工具 X clear

console

<div class="demo-wrap">
  <div class="demo-center"></div>
</div>

.demo-wrap{
	width:300px;
	height:300px;
	background:#eee;
	display:flex
}
.demo-center{
	width:200px;
	height:200px;
	background:#999;
	margin:auto
}