纯CSS控制不固定宽高图片div内水平垂直均居中 (http://sandbox.runjs.cn/show/c9zvoil2)

center-image.html

<style>
.img-outSide{
    width: 500px;
    height: 750px;
    border: 1px solid #CDCDCD;
    text-align: center;
}
.img-inSide,.img-con{
    display: inline-block;
    vertical-align: middle;
}
.img-inSide{
    height: 100%;
}
</style>

<div class="img-outSide">
  <a href="#" class="img-con">
    <img style="float: left;"  src="http://sandbox.runjs.cn/uploads/rs/234/k0xxr73w/1.jpg" />
  </a>
  <b class="img-inSide"></b>
</div>