So I don’t make that same mistake again, can one of you explain why I needed to set the margin: auto, and padding: 0 in my body tag? What does "auto" do in CSS?
you need to understand the box modal really.
(this is how I look at it)
think of a product like a TV
TV is the content
padding is the stuff between the TV and the box
Border is the box it comes in
and margin is the space that box sites from the edge of the room (if that makes sense)
so you set your margin to have a set size, if you want it to be a certain size e.g. in the centre you use auto, (no matter what size).