animatins.css

  div {
    animation-name: 'diagonal-slide';
    animation-duration: 5s;
    animation-iteration-count: 10;
  }

  @keyframes 'diagonal-slide' {

    from {
      left: 0;
      top: 0;
    }

    to {
      left: 100px;
      top: 100px;
    }

  }