方法一、table-cell
<div class="lg-cont">
<img src="111.png">
</div>
.lg-cont{height:200px;width:100%;display:table-cell;vertical-align:middle;}
方法二、flex布局
<div class="lg-cont">
<img src="111.png">
</div>
.lg-cont{height:200px;width:100%;display:flex;justify-content:center;align-items:center;}
方法三、绝对定位
<div class="lg-cont">
<img src="111.png">
</div>
.lg-cont{position:relative;}
.lg-cont img{position:absolute;width:100px;height:100px;top:50%;left:50%;margin-left:-50px;}
方法四、translate
<div class="lg-cont">
<img src="111.png">
</div>
.lg-cont{position:relative;}
.lg-cont img{position:absolute;width:100px;height:auto;top:50%;left:50%;transform:translate(-50%,-50%);}
