chore: fix formatting, remove jQuery, and switch to HTML5 doctype

1. I don't think jQuery is needed, but I might have missed something.
1. Switched the mix of tabs and spaces to all spaces with two space indentation
1. Used HTML5 specifications - The center element is deprecated and should be replaced with CSS in the future.

Q. Is there any reason to not split up the JS and HTML? I can make another pull request doing that, while also creating a CSS file.

Definitely an interesting/cool idea.