JSFiddle - React, Tailwind, and code Playground

HTML

<p class="shadow">Текст</p>

<!-- Пример сайта know-online.com -->

CSS

.shadow {
  box-shadow: inset 3px 3px 8px #333;
  
  background: #c2c2c2;
  padding: 10px;
  width: 300px;
  margin: 20px auto 0;
}

body {
  font: 14px verdana, sans-serif;
}