弹性布局
1.父级弹性布局，子级margin: auto;
<html>
<div class="main">
<div class="children"></div>
</div>
<style>
.main{
width: 100%;
height: 100%;
border: 1px solid #ABCDEF;
display: flex;
}
.children{
width: 100px;
height: 100px;
background: #CBA;
margin: auto;
}
</style>
</html>
2.父级弹性布局，同时设置justify-content:center;align-items:center
<style>
.main{
width: 100%;
height: 100%;
border: 1px solid #ABCDEF;
display: flex;
justify-content:center;
align-items:center
}
</style>
子绝父相
设置子元素top/left/right/bottom: 0,margin:auto
<html>
<div class="main">
<div class="children"></div>
</div>
<style>
.main{
width: 100%;
height: 100%;
border: 1px solid #ABCDEF;
position: relative;
}
.children{
width: 100px;
height: 100px;
background: #CBA;
top:0;
left: 0;
bottom: 0;
right: 0;
margin: auto;
position: absolute;
}
</style>
</html>
设置transform: translate: (-50%,-50%),left:50%,top:50%
.children{
width: 100px;
height: 100px;
background: #CBA;
top:50%;
left: 50%;
transform: translate(-50%,-50%);
position: absolute;
}
margin负值法(需要知道子元素宽高)
.children{
width: 100px;
height: 100px;
background: #CBA;
top:50%;
left: 50%;
margin: -50px -50px;
position: absolute;
}
父子元素宽高确定的情况
父元素设置display:table-cell vertical-align:middle，子元素设置:margin: 0 auto
<style>
.main{
width: 300px;
height: 300px;
border: 1px solid #ABCDEF;
display: table-cell;
vertical-align: middle;
}
.children{
width: 100px;
height: 100px;
background: #CBA;
margin: 0 auto;
}
</style>
