em {
    position: relative;
    font-family: verdana;
    letter-spacing: 3px;
    overflow: hidden;
    background: linear-gradient(90deg, #000, #fff, #000);
    background-repeat: no-repeat;
    background-size: 80%;
    animation: animate 15s linear infinite;
    -webkit-background-clip: text;
    -webkit-text-fill-color: rgba(255, 255, 255, 0);
  }
  
  @keyframes animate {
    0% {
      background-position: -500%;
    }
    100% {
      background-position: 500%;
    }
  }