wp_head is breaking my fullPage.js video

I’m using https://github.com/alvarotrigo/fullPage.js on a blank theme that I am using as a base for my theme/design.

I’m using the video to show on a full page (https://alvarotrigo.com/fullPage/examples/videoBackground.html). However, it doesn’t work on Safari and on Chrome, it doesn’t take up the whole screen. If I remove <?php wp_head(); ?> from my page, the video shows up properly.

I’m looking for any advice on this. What can I change in the CSS from https://alvarotrigo.com/fullPage/examples/videoBackground.html to have the video show up properly without having to edit <?php wp_head(); ?>

Thank you in advance.