JSFiddle - React, Tailwind, and code Playground

HTML

<div>Загрузить ещё</div>

CSS

div {
  position: relative;
  display: inline-block;
  padding: 10px 15px;
  background: #3B2142;
  color: white;
  border-radius: 8px;
  border: 2px solid white;
}
div:before {
    content: " ";
    border-radius: 8px;
    position: absolute;
    z-index: -1;
    top: -5px;
    left: -5px;
    right: -5px;
    bottom: -5px;
    border: 2px solid black;
}