JSFiddle - React, Tailwind, and code Playground

HTML

<div class="page">
    Lorem ipsum etc etc etc. 
</div>

<button>toggle fade</button

CSS

.page {
          -moz-animation-name: fadeIn;
          -webkit-animation-name: fadeIn;
          -ms-animation-name: fadeIn;
          animation-name: fadeIn;
          -moz-animation-duration: 1s;
          -webkit-animation-duration: 1s;
          -ms-animation-duration: 1s;
          animation-duration: 1s;
          -moz-animation-timing-function: ease-in-out;
          -webkit-animation-timing-function: ease-in-out;
          -ms-animation-timing-function: ease-in-out;
          animation-timing-function: ease-in-out;
          -moz-animation-fill-mode: forwards;
          -webkit-animation-fill-mode: forwards;
          -ms-animation-fill-mode: forwards;
          animation-fill-mode: forwards;  
        }
        
        .page.fadeOut {
          -moz-animation-name: fadeOut;
          -webkit-animation-name: fadeOut;
          -ms-animation-name: fadeOut;
          animation-name: fadeOut;
        }
        
        @-moz-keyframes fadeIn { 0% { opacity: 0; visibility: hidden; } 100% { opacity: 1; visibility: visible; }}
        @-webkit-keyframes fadeIn { 0% { opacity: 0; visibility: hidden; } 100% { opacity: 1; visibility: visible; }}
        @-ms-keyframes fadeIn { 0% { opacity: 0; visibility: hidden; } 100% { opacity: 1; visibility: visible; }}
        @-keyframes fadeIn { 0% { opacity: 0; visibility: hidden; } 100% { opacity: 1; visibility: visible; }}
    
        @-moz-keyframes fadeOut { 0% { opacity: 1; visibility: visible; }  100% { opacity: 0; visibility: hidden; }} 
        @-webkit-keyframes fadeOut { 0% { opacity: 1; visibility: visible; }  100% { opacity: 0; visibility: hidden; }} 
        @-ms-keyframes fadeOut { 0% { opacity: 1; visibility: visible; } 100% { opacity: 0; visibility: hidden; }} 
        @-keyframes fadeOut { 0% { opacity: 1; visibility: visible; } 100% { opacity: 0; visibility: hidden;  }}

JavaScript

$('button').click(function() { $('.page').toggleClass('fadeOut');});