JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
  <div class="content">Coucou</div>
</div>

CSS

.wrapper {
  padding: 2px;
  background: rgb(0,0,0);
  background: linear-gradient(90deg, rgba(0,0,0,1) 0%, rgba(255,255,255,1) 60%);
  border-radius: 5px;
}
.content {
  padding: 10px;
  background: #FFF;
  border-radius: 3px;
}