Today I read a short article on a subject I knew at one point, but feels fresh to remember.
The article was Meet border-box, my best friend.
It describes the difference between
box-sizing: border-box and
content-box means that only content (and not padding & borders) use the height & width values on the element.
border-box is the value for
box-sizing, a div that is set to say,
width: 200px and has a 6 pixel border will actually be 200 pixels from border edge to border edge, not 212 pixels like it would be if you were using