img在div中上下左右居中 ​

<div id="aa">
<img src='xxxx.png'>
</div>

<div id="aa">
<img src='xxxx.png'>
</div>

#aa{
    display: flex;
    align-items: center;
    justify-content: center;
}

#aa{
    display: flex;
    align-items: center;
    justify-content: center;
}