You have something in you CSS that is overriding Bootstrap. I was messing around and pulled your styles and tried to play with my Bootstrap with your code. Nothing worked until I deleted all your styles; then it did it stack. It confused me because I use W3schools to test my pages, when I tried your code in their page, it worked fine.
You’re going to have to change whatever entity you’re overriding Bootstrap. That’s just for #1. However, it might apply to your other codes as well.