Boxsizing Examples
Example 1 - No box sizing
This div is smaller (width: 300px; height: 100px).
This div is bigger (width: 300px; height: 100px; border: 50px).
Example 2 - box-sizing: border-box
Both divs are the same size now! (width: 300px; height: 150px; box-sizing: border-box)
(width: 300px; height: 150px; border: 50px; box-sizing: border-box)