html{
    height: 100%;
  }
  body{
    margin: 0;
  }
  .plano-fundo{
    animation: animacao 3s ease-in-out 
    infinite alternate;
    background: linear-gradient(-20deg,
    rgb(62, 29, 122) 50%, rgb(144, 218, 231) 50%);
    bottom: 0;
    left: -100%;
    opacity: .5;
    position: fixed;
    right: -50%;
    top: 0;
    z-index: -1;
  }
  .pf1{
    animation-direction: alternate-reverse;
    animation-duration: 4s;
  }
  .pf2{
    animation-duration: 5s;
  }
  .quadrado{
    background-image: image(img/img1.jpg);
    border-radius: .25em;
    box-sizing: border-box;
    opacity: 60%;
    left: 50%;
    padding: 10vmin;
    position: fixed;
    text-align: center;
    top: 50%;
    transform: translate(-50%, -50%);
  }
  h1{
    font-family: monospace;
  }
  @keyframes animacao{
    0%{
      transform: translateX(-25%);
    }
    50%{
      transform: translateX(50%);
    }
    100%{
      transform: translateX(25%);
    }
  }