<div class="container">
  <div class="center"></div>
</div>

.container {
  width: 300px;
  height: 300px;
  outline: 2px solid blue;
  margin-top: 100px;
}

.center {
  width: 50px;
  height: 50px;
  outline: 1px solid red;
  margin-top: 80px;
  
}