Question

I’ve searched the W3C CSS2 Spec for the name of the feature that allows us to shrink duplicate values down to one or two like:

margin: 1px 1px 1px 1px;  -> margin: 1px;
padding: 1px 1px 2px 2px; -> padding: 1px 2px;

But I’m still not sure what the exact name for this is. Does anyone know what this is called? Also, can you list some other properties that follow this behavior (besides the obvious ones like margin, padding, and border-radius). I’m writing a regex that matches these properties and would like to include as many them as possible!

Thanks!

Answer 1

margin is a shorthand property for margin-left, margin-top, etc.
margin: 1px 1px 1px 1px; and margin: 1px; are both shortcuts. In the later one for values collapsed into one. So collapsing probably.

As of other shorthands:

• size property (from printing module)
• border-width, border-color and border-style
• background-position, background-size, etc.