SOURCE

<div class="war">
  <div class="box">
    <div class='map'>
      中心点
    </div>
  </div>
</div>

*{
  margin:0px;
  padding:0px;
}
.war{
  width:600px;
  margin:0px auto;
}
.box{
  width:300px;
  height:200px;
  background-color:#ccc;
  position:relative;
  overflow:hidden; // 遮盖
}
.map{
  width:500px;
  height:300px;
  background-color:#1c90f3;
  position:absolute;
  top:50%;
  left:50%;
  transform:translate(-50%,-50%);
  
  text-align:center;
  line-height:300px;
}