<style>
   .box-right {
      height: 300px;
      margin-left: 300px;
      background-color: brown
   }

   .box-left {
      width: 300px;
      height: 300px;
      float: left;
      background-color: black;
   }
</style>

<body>
   <div class="box-left">
      <a href="">我是左面</a>
   </div>
   <div class="box-right">
      <a href="">我是右面</a>
   </div>
</body>
定位