小编Thi*_*ira的帖子

.main {
  background-color: black;
  width: 100%;
  height: 1250px;
  position: relative;
}

.container{
  display: block;
  position: absolute;
  width: 250px;
  height: 650px;
  background: white;
}

.red-box{
  background: red;
  width: 150px;
  height: 140px;
  position: fixed;
}

<div class="main">
  <div class="container">
    <div class="red-box">
    </div>
  </div>
</div>