This property specifies how to apply the width and height of the content box to the element. The value "content-box" (the initial value) is the behavior specified by CSS 2.1, while "border-box" is the common implementation of legacy browsers for replaced elements and input elements.
CSS Level | Value |
---|---|
CSS 2.1 | (invalid) |
CSS3 | "content-box", "padding-box", or "border-box" |