console 命令行工具 X clear

console

<div class="wrapper">

    <div class="content"></div>
</div>

.wrapper{
    height: 900px;
    position: relative;
    background-color: grey;

}

.content{
    height: 400px;
    width: 400px;
    background-color: red;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%)
}