JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">

</div>

CSS

body {
   background:pink;
}

.box {
  width:300px;
  height:200px;
  -webkit-mask:
    linear-gradient(#000 0 0) top         /100% 70%,
    linear-gradient(#000 0 0) bottom right/70% 20%,
    radial-gradient(circle closest-side,#000 90%,#0000) bottom left/25% 25%;
  -webkit-mask-repeat:no-repeat;
  background:linear-gradient(90deg,#ccca 40%,#fffa ,#ccca 60%) right/300% 100% ;
  animation: m 1s linear infinite;
}
@keyframes m {
  to {background-position:left;}
}