JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container"></div>

CSS

* {
  margin: 0;
  padding: 0;
  border: none;
  outline: hidden;
  font-size: 0;
  box-sizing: border-box;
  overflow: hidden;
}
.container {
  width: 50vw;
  height: 50vw;
    border: 5px double white;
  background: -moz-linear-gradien(top, #a90329 0%, #e3f704 10%, #ed0408 19%, #b804f9 29%, #04daf2 39%, #8f0222 49%, #cc048c 59%, #0407d6 69%, #8f0222 80%, #04e034 91%, #6d0019 100%);
background: -webkit-linear-gradient(top, #a90329 0%,#e3f704 10%,#ed0408 19%,#b804f9 29%,#04daf2 39%,#8f0222 49%,#cc048c 59%,#0407d6 69%,#8f0222 80%,#04e034 91%,#6d0019 100%);
background: linear-gradient(to bottom, #a90329 0%,#e3f704 10%,#ed0408 19%,#b804f9 29%,#04daf2 39%,#8f0222 49%,#cc048c 59%,#0407d6 69%,#8f0222 80%,#04e034 91%,#6d0019 100%);
}