@media (min-width: 768px) {
  header,
  main,
  .centered-div,
  #start-button,
  #end-button,
  #game-options-container {
    font-size: 1.2em;
  }

  select {
    font-size: 0.85em;
  }

  #game-container {
    width: 500px;
    height: 500px;
  }
  #game-target {
    width: 400px;
    height: 400px;
  }

  #site-intro {
    width: 50%;
    margin: inherit auto;
  }

  .centered-div,
  #site-footer aside {
    width: 50%;
    margin: 0 auto;
  }
}