When I develop in CSS, I make a habit of removing all predetermined padding, margins, or borders by simply declaring this at the top of my CSS file.
* {
     padding:0;
     margin:0;
     border:0;
}
Beginners learning CSS will commonly run into the problem of random spacing issues because every element has some form of formatting associated with it. [...]

Have you ever started working on something, only to have to come to failure? I know, I know…. It has been riddled into your brains since you were in elementary math when the teacher docked your grade for not writing out your solutions/methods when you simply answered the question!
It is a hard habit to break, [...]