小的div在大的div中垂直居中

<div style="width:200px;height:200px;border:solid blue;position:relative;">
<div style="width:100px;height:100px;margin: auto;  position: absolute;  top: 0; left: 0; bottom: 0; right: 0; background: red;"></div>
</div>

<div style="width:200px;height:200px;border:2px solid #000;display:table-cell;vertical-align:middle;text-align: center;">
<div style="width:100px;height:100px;display:inline-block;background-color: red;"></div>
</div>

<div style="width:200px;height:200px; border:2px solid #000;display:flex;justify-content:center;align-items:center;">
<div style="width:100px;height:100px;background-color: red;"></div>
</div>

<div style="width:200px;height:200px; border:2px solid #000;position:relative;">
<div style="width:100px;height:100px;margin:auto;position:absolute;left:50%;top:50%;margin-left: -50px;margin-top:-50px;background-color: red;"></div>
</div>