JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer-tray">
<div class="tray">
    <div class="fill"></div>
</div>
</div>

CSS

body {
    background: #ccc;
}
.tray {
  /* overflow: hidden; */
  height: 20px;
  background: #000;
  border-radius: 50px;
  height: 30px;
  width: 100%;
  border: none solid transparent;
  background-color: black;
}
.fill {
  background: #fff;
  width: 10%;
  border-radius: 100px;
  left: -1px;
  position: relative;
  float: left;
  box-sizing: border-box;
  border: 1px solid white;
  top: -1px;
  height: 32px;
}
.outer-tray {
    overflow: hidden;
  border-radius: 100px;
  overflow: hidden;
  display: block;
}