html {
    background: orange;
    font-family: sans-serif;
    height: 100%;
  }
  
  body {
    height: inherit;
    width: 80%;
    min-width: 500px;
    max-width: 1000px;
    margin: 0 auto;
  }
  
  .controls {
    display: flex;
    justify-content: space-around;
    align-items: center;
  }
  
  div button {
    flex: 1;
    margin: 20px;
    height: 30px;
    line-height: 30px;
  }
  
  .box {
    display: flex;
    justify-content: center;
    align-items: center;
    height: calc(100% - 70px);
  }
  
  .box p {
    width: 50%;
    text-align: center;
    font-weight: bold;
    font-size: 40px;
    height: 150px;
    line-height: 150px;
    background: red;
    border: 5px solid purple;
    color: white;
    transition: all 1s;
  }