html结构:
<div class="parent">
<div class="child"></div>
</div>
方法一： display:flex
.parent {
width: 500px;
height: 500px;
background: red;
display: flex;
align-items: center;
justify-content: center;
}
.child {
width: 100px;
height: 100px;
background: blue;
}
方法二：display:table-cel
.parent{
width: 500px;
height: 500px;
background: red;
display: table-cell;
vertical-align: middle;
}
.child{
width: 100px;
height: 100px;
background: blue;
margin: auto;
}
方法三：绝对定位和0
.parent{
width: 500px;
height: 500px;
background: red;
position: relative;
}
.child{
width: 100px;
height: 100px;
background: blue;
margin: auto;
position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 0;
}
方法四：负边距
.parent{
width: 500px;
height: 500px;
background: red;
position: relative;
}
.child{
width: 100px;
height: 100px;
background: blue;
position: absolute;
top: 50%;
left: 50%;
margin-left: -50px;
margin-top: -50px;
}
以上四种方法都可以完成用css实现子元素在父元素实现水平和垂直居中。
