Is the border thickness added to the box height and width?
It is important to realize that there is a distinction between the rendered height and width of an element and the
height properties of an element. By default, the
height properties only affect the content area of a box. This means that while the
margin properties do affect the rendered dimensions of an element they do not factor into the width and height of a box’s content area as specified by the
As you will learn in the next lesson, this default behavior can be modified with the
box-sizing: border-box; declaration.