JSFiddle - React, Tailwind, and code Playground

HTML

<div id="loading_bar">
    <div id="buffer" style="width:40%"></div>
    <div id="progress" style="width:20%"></div>
</div>

CSS

body {
  margin: 5px;
}

#loading_bar{
  width:660px;
  overflow:hidden;
  height:80px;
  border:2px solid red;
  border-radius:80px;
  background-color:#666;
  position:relative;
}

#buffer, #progress {
  height:40px;
}

#buffer {
  background-color:#0474C0;
}

#progress {
  background-color:pink;
}