<div class="container">
  <span data-title="HelloWorld!" class="text">
    HelloWorld!
  </span>
</div>

body{
  
@import url('https://fonts.googleapis.com/css2?family=Fjalla+One&display=swap');
  margin: 0;
  padding: 0;
  overflow: hidden;
  font-family: 'Fjalla One', sans-serif;
}

.container{
  margin: 0 auto;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #d1dae3;
  .text{
    color: transparent;
    font-size: 10vw;
    display: inline-block;
    border-radius: 3px;
    background-color: #1d3557;
    position: relative;
    -webkit-background-clip: text;
    background-clip: text;
    &:before{
      content: attr(data-title);
      background: linear-gradient(90deg, rgba(245,137,21,1) 0%, rgba(253,29,29,1) 51%, rgba(29,53,87,1) 100%);
      position: absolute;
      top: 0;
      right: 0;
      bottom: 0;
      left: 0;
      width: 0;
      background-clip: text;
      -webkit-background-clip: text;
      transition: all 1s ease-in-out;
      animation: text-animation 3s infinite;
    }
  }
}

@keyframes text-animation{
  0%{
    width: 0;
  }
  50%{
    width: 100%;
  }
  100%{
    width: 0;
  }
}