<div class="parent">
<div class="children">我是通过flex的水平垂直居中噢！<br/>我是通过flex的水平垂直居中噢！</div>
</div>
html,body{
100%;
height: 200px;
}
.parent {
display:flex;
align-items: center;/*垂直居中*/
justify-content: center;/*水平居中*/
100%;
height:100%;
background-color:red;
}
.children {
background-color:blue;
}