JSFiddle - React, Tailwind, and code Playground

by Yuriy Petrichenko

HTML

<hr>

CSS

hr{
  background-color:black;
  height:3px;
  border:none;
  width:400px;
  margin-left:0px;
  animation: masive 1s linear;
  transition-delay: 4s;
}
@keyframes masive {
    0% {
        width: 100px;
    }
    100% {
        width:400px;
        background-color:red;
    }
}