style.css

body{
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}
#preSourceCode{
    position: absolute;
    left:10px;
    top:10px;
    bottom:10px;
    right:50%;
    z-index:1;
    margin: 0;
    overflow: hidden;
    font-size: 100%;
}
.hljs{
    background-color: rgba(255,255,255,0) !important;
}

#scroll-container {
    border: 3px solid black;
    border-radius: 5px;
    height: 100px;
    overflow: hidden;
  }
  
  #sourceCode {  
    overflow: hidden; 
    transform: translateY(10%); 
    opacity:0;   
    animation: my-animation 30s linear infinite;
  }

  @keyframes my-animation {
    0%   {transform: translateY(10%);opacity: 0;}
    25%  {opacity: 1;}
    50%  {}
    75%  {opacity: 1;}
    100% {transform: translateY(-100%);opacity: 0;}
  }