<div class="container">
  <div class="element">
    This is content
  </div>
</div>

.container { 
  display: grid;
  height: 400px;
  place-items: center;
  border: 3px solid green; 
}

.container .element {
  width: 150px;
  height: 150px;
  background-color: red;
}