css让一个容器水平垂直居中

方法一：position加margin 兼容性：主流浏览器均支持，IE6不支持
.wrap {
width: 200px;
height: 200px;
background: yellow;
position: relative;
}
.wrap .center {
width: 100px;
height: 100px;
background: green;
margin: auto;
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
}

方法二： diaplay:table-cell 兼容性：由于display:table-cell的原因，IE6\7不兼容
.wrap{
width: 200px;
height: 200px;
background: yellow;
display: table-cell;
vertical-align: middle;
text-align: center;
}
.center{
display: inline-block;
vertical-align: middle;
width: 100px;
height: 100px;
background: green;
}

方法三：position加 transform 兼容性：ie9以下不支持 transform，手机端表现的比较好。
.wrap {
position: relative;
background: yellow;
width: 200px;
height: 200px;}

.center {
position: absolute;
background: green;
top:50%;
left:50%;
-webkit-transform:translate(-50%,-50%);
transform:translate(-50%,-50%);
width: 100px;
height: 100px;
}
方法四：flex;align-items: center;justify-content: center 移动端首选
.wrap {
background: yellow;
width: 200px;
height: 200px;
display: flex;
align-items: center;
justify-content: center;
}
.center {
background: green;
width: 100px;
height: 100px;
}
方法五：display:flex;margin:auto 移动端首选
.wrap {
background: yellow;
width: 200px;
height: 200px;
display: flex;
}
.center {
background: green;
width: 100px;
height: 100px;
margin: auto;
}
方法六：纯position 适用于所有浏览器
.wrap {
background: yellow;
width: 200px;
height: 200px;
position: relative;
}
/方法一/
.center {
background: green;
position: absolute;
width: 100px;
height: 100px;
left: 50px;
top: 50px;
　　
}
/方法二/
.center {
background: green;
position: absolute;
width: 100px;
height: 100px;
left: 50%;
top: 50%;
　　margin-left:-50px;
　　margin-top:-50px;
}