i used the inspector and put stuff in the head, body, and CSS as directed. I replaced the file names with my own. I get 3 boxes like a table but that is all. And it screws up the rest of the CSS.
Custom CSS is definitely not my forte but, I wonder if you used something like this (https://joeworkman.net/rapidweaver/stacks/css-box/) to apply the CSS to one component on the page, and not anything else?