Custom 404 images problems

Hello,

I created a 404 page for my website in photoshop. When I try the page on a fake html page in the root directory of the server (example.com/lol.html), everything works perfectly. But when I try the page with a fake html page that is located in a directory on the server (example.com/videos/lol.html), the page comes up but the images that make the page look good aren't. How can I get those images to show up on the 404 page in every condition.
My website runs on my own ubuntu server with a LAMP solution.