<div class=”box”>
<img class=”img”/>
</div>
.box{ position: relative;}
.img{ width: 100%;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);}
<div class=”box”>
<img class=”img”/>
</div>
.box{ position: relative;}
.img{ width: 100%;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);}