Where to place HTML and JS code for a pre-loader screen in Dawn theme?

[rtmvp]

Hello,

I have written HTML code combined with JS for animation purposes but do not understand where should the code be placed in order to have an opening scene on my shopify store with Dawn theme. The code is taking image as a source from the folder on my dekstop, therefore, I am interested whether that would even work if I place the code in the theme.

Pasting the code down below, would be interested to receive some feedback whether it works and if it should work, where the code should be placed. Many thanks in advance!

Fading Logo with Slide-in Effect /* CSS for the logo */ #logo { position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%); opacity: 1; transition: opacity 1s ease-in-out; }