console 命令行工具 X clear

console

<div class="outside">
    <div class="inside"></div>
</div>

div.outside {
    background-color: skyblue;
    width: 350px;
    height: 350px;

    display: table-cell;
    vertical-align: middle;
}

div.inside {
    background-color: lightcoral;
    width: 100px;
    height: 100px;

    margin: auto;
}