css垂直居中

.box4 span{...}{

  width: 50%;  

  height: 50%;  

  background: #000;

  overflow: auto;  

  margin: auto;  

  position: absolute;  

  top: 0; left: 0; bottom: 0; right: 0;  

}

		

.box1{...}{

    display: table-cell;

    vertical-align: middle;

    text-align: center;         

}

				

.box3{...}{position:relative;}
.box3 span{...}{
            position: absolute;
            width:100px;
            height: 50px;
            top:50%;
            left:50%;
            margin-left:-50px;
            margin-top:-25px;
            text-align: center;
        }

		

.box7{...}{

  text-align:center; 

  font-size:0;

}

.box7 span{...}{

  vertical-align:middle; 

  display:inline-block; 

  font-size:16px;

}

.box7:after{...}{

  content:'';

  width:0;

  height:100%;

  display:inline-block;

  vertical-align:middle;

}

		

<style type="text/css">...
.con_li{...}{
width:400px;
height:300px;
border:1px solid #777;
text-align:center;
display:table-cell;
vertical-align:middle;
background:red;
color:#fff;
line-height:300px;
}
</style>

<li class="con_li">
测试内容ddddddddddd
</li>

		

.box2{...}{

    display: flex;

    justify-content:center;

    align-items:Center;

}