CSS
  .flex-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    max-width: 1000px;
    margin: 0 auto;
    padding: 1%;
  }
  
  .flex-item {
    width: 30%;
    max-width: 275px;
    min-width: 200px;
    margin-left: 1%;
    margin-right: 1%;
  }
  
  .image {
    width: 100%;
    height: auto;
  }
HTML
<div class="flex-container">

  <a class="flex-item" href="http://example-url.org">
    <img class="image" src="http://example-image.jpg">
    <h3 class="pic-title">Spirograph Nebula</h3>
  </a>

  <!--Each of the nine flex items follow the format above-->

</div>