Preloader screen on Squarespace website design

I have a Gif animation that I want as a preloader screen while homepage loads in background. Further detail: The homepage has a video that needs 4-5 seconds to load. So I want to have a GIF play with a solid background to hide homepage while it loads. I want the preloader screen to be on same page without a redirect to homepage. Custom code is needed for squarespace. To win the bid you will have direct me to a website that is hosted by squarspace where you have used custom code to achieve preloader screen. Thank you.