Change background image of a page on a mouse hover over a button

Site URL: https://viktoriapezzei.com/home-overview

I would like to create a page, which is inspired by this one. As soon as you hover over a button, the background image of the whole page should change. I'm using the Birne template on Squarespace 7.0 and have a Business plan, hense I'm able to add code to the page itself. 

Is there any possibility to add a html style tag for this purpose?