If you’re trying to figure out how to do any styling in your game, I highly recommend learning how to use the “Developer Tools” window in your desktop browser. If you look in the latter half of my comment here, I explain how to use it to find existing styling on a page and how to test various style settings before adding those changes to your game’s Stylesheet section.
Using that method should make styling your page way easier to figure out.
Hope that helps! 