Allows you to define horizontal and vertical offsets to change the origin, or anchor point, of the transform.
This box is rotated using CSS3 transforms, but the origin of the rotation is changed from the default center.
Three-value Standard Syntax:
Firefox 16+, IE10+
Three-value Vendor Syntax:
Firefox 10+, Chrome (?), Safari (?)
Standard Syntax:
IE10+, Opera 12.1+
Vendor Prefix:
IE9+, Firefox 3.5+, Chrome 4+, Safari 3.1+, Opera 10.5+
A Primer on CSS3 Transforms (SitePoint)
transform-origin on MDN