JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
  height: 1000px;
  position: relative;
  overflow: hidden;
}

div:before {
  content: '';
  display: block;
  position: absolute;
  top: -60px;
  left: 10px;
  width: 3px;
  height: calc(100% + 60px);
  background: repeating-linear-gradient(to bottom, rgba(255, 255, 255, 0) 0px, rgba(255, 255, 255, 0) 30px, #007dff 30px, #007dff 60px);
  animation: slide 2s infinite linear;
}

@keyframes slide {
    0% { transform: translateY(0) }
    100% { transform: translateY(60px) }
}

body {
  margin: 0 30px;
}