将子div保留在父div内

<style>
    .parent {
        position: relative;
        width: 300px;
        height: 200px;
        border: 1px solid #000;
        overflow: hidden;
    }
    .child {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        width: 200px;
        height: 100px;
        background-color: #ccc;
    }
</style>

<div class="parent">
    <div class="child"></div>
</div>

<style>
    .parent {
        display: flex;
        justify-content: center;
        align-items: center;
        width: 300px;
        height: 200px;
        border: 1px solid #000;
    }
    .child {
        width: 200px;
        height: 100px;
        background-color: #ccc;
    }
</style>

<div class="parent">
    <div class="child"></div>
</div>