* {
    margin: 0;
    padding: 0;
  }
  :root {
    --facebook: #3b5998;
  }
  .wrap-all {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
  }
  .play-time {
    font-size: 3rem;
    margin-top: 2rem;
    clear: var(--facebook);
  }
  ul {
    margin-top: 1rem;
    list-style: none;
    border: 2px solid var(--facebook);
    display: grid;
    grid-template-columns: repeat(4, 1fr);
  }
  li {
    width: 100px;
    height: 100px;
    color: #fff;
    background: url("http://placeimg.com/400/400/animals/grayscale");
  }
  .start-button {
    background: var(--facebook);
    color: #fff;
    border: none;
    padding: 1rem 2rem;
    margin-top: 1rem;
  }
  .game-text {
    position: absolute;
    font-size: 45px;
    color: #67c23a;
    text-shadow: 1px 1px rgba(0, 0, 0, 0.5);
    display: none;
  }
  .list1 {
    background-position-x: -100px;
    background-position-y: 0px;
  }
  .list2 {
    background-position-x: -200px;
    background-position-y: 0px;
  }
  .list3 {
    background-position-x: -300px;
    background-position-y: 0px;
  }
  .list4 {
    background-position-x: 0px;
    background-position-y: -100px;
  }
  .list5 {
    background-position-x: -100px;
    background-position-y: -100px;
  }
  .list6 {
    background-position-x: -200px;
    background-position-y: -100px;
  }
  .list7 {
    background-position-x: -300px;
    background-position-y: -100px;
  }
  .list8 {
    background-position-x: 0px;
    background-position-y: -200px;
  }
  .list9 {
    background-position-x: -100px;
    background-position-y: -200px;
  }
  .list10 {
    background-position-x: -200px;
    background-position-y: -200px;
  }
  .list11 {
    background-position-x: -300px;
    background-position-y: -200px;
  }
  .list12 {
    background-position-x: 0px;
    background-position-y: -300px;
  }
  .list13 {
    background-position-x: -100px;
    background-position-y: -300px;
  }
  .list14 {
    background-position-x: -200px;
    background-position-y: -300px;
  }
  .list15 {
    background-position-x: -300px;
    background-position-y: -300px;
  }
  .list16 {
    background-position-x: -200px;
    background-position-y: -300px;
  }