console 命令行工具 X clear

console

<div class="box1">
    <div class="box2"></div>
</div>

.box1 {
    position: relative;
    top: 50px;
    left: 50px;
    background-color: red;
    width: 200px;
    height: 200px;
    overflow: hidden;
}

.box2 {
    position: fixed;
    top: 50px;
    left: 50px;
    background-color: green;
    width: 200px;
    height: 200px;
}