* {
    box-sizing: border-box;
    background-color: black;
  }
  
  body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
  }
  
  .header {
    text-align: center;
    padding: 30px;
    margin-left: auto;
    margin-right: auto;
    font-size: 60px;
    font-weight: 700;
    color: white;
    background-color: black;
  }

  .greeting{
      display: block;
      text-align: center;
      color: white;
      background-color: black;
  }
  
  .row {
    display: -ms-flexbox; /* IE 10 */
    display: flex;
    -ms-flex-wrap: wrap; /* IE 10 */
    flex-wrap: wrap;
    padding: 0 4px;
  }
  
  /* Create two equal columns that sits next to each other */
  .column {
    -ms-flex: 50%; /* IE 10 */
    flex: 50%;
    padding: 0 4px;
  }
  
  .column img {
    margin-top: 8px;
    vertical-align: middle;
  }
  
  .photo-grid-container{
      padding-top: 40px;
      column-count: 2;
      padding-left: 10px;
      padding-right: 10px;
      column-width: 200px;
      column-gap: 10px;
      width: 100%;
      max-width: 1600px;
      margin: auto;
  }

  .photo-grid-item{
      margin: 0 auto 5px;
      width: 100%;
  }
  
  a:hover{
    opacity: 0.6;
  }