Logo loading screen - code adjustment please

Hi everyone, 

I bought a plugin from Squarestud.io and it appears that they dont respond to anyone's emails/facebook/instagram - I assume they have gone bust. Anyway, I need to tweak the plugin and I am not very good at .js and would appreciate some help. 

The plugin is a logo loading screen using the site's logo.  I am wanting to replace the image source (the existing site logo) with a gif that is stored in the site's CSS stored files - URL below.

Any help is really really really appreciated.

Thank you, 

Rob 
working site: https://pepper-clarinet-ctnt.squarespace.com/

GIF: 

https://static1.squarespace.com/static/5d9db9630e0cb109b5331185/t/5db877bc05d8093cb6fbfe15/1572370384602/mrnice-smiley.gif

Code Injection: 

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
<div class="logoload"></div>
<script>
$(function() {
  var loadLogo = $('header').find('img').attr('src');
  $('.logoload').css('background-image', 'url(' + loadLogo + ')');
});
</script>
<style>
.logoload {
  /* SET BACKGROUND COLOR */
  background-color: #fff;
  /* SET BACKGROUND SIZE */
  background-size: 90px;
  position: fixed;
  left: 0px;
  top: 0px;
  width: 100%;
  height: 100%;
  z-index: 9999;
  background-position: center;
  background-repeat: no-repeat;
}
</style>
<script type="text/javascript">
$(window).load(function() {
    $(".logoload").delay(500).fadeOut("slow");
})
</script>