JSFiddle - React, Tailwind, and code Playground

HTML

<div class="pre-load">
  <img src="https://i.stack.imgur.com/IaDfI.gif" width="30px" height="32px">
</div>
<div class="container none">
   <h1>Hello World!</h1>
</div>

CSS

.none{
  display:none;
}

.pre-load{
  position:fixed!important;
  width:100%;
  height:100%;
  top:0;
  left:0;
  background-color: #FFFFFF;
  z-index:99999;
}

.pre-load > img{
  margin-top: 30%;
}

JavaScript

// fake retard process
setTimeout(function(){
// container show
document.getElementsByClassName("container")[0].removeAttribute("class");

// pre-load blocker hide
document.getElementsByClassName("pre-load")[0].setAttribute("class","none");
}, 3000);