Summary
Shapes can be specified for shape-outside with a <shape-box> type, which is a reference to edges in the CSS Box Model. 
Possible Values
margin-box
Defines the shape enclosed byt the outside margin edge. The corner radii of this shape are determined by the corresponding border-radius and margin values. If the border-radius / margin is 1 or more, then the margin box corner radius is border-radius + margin. If the ratio of border-radius / margin is less than 1, then the margin box corner radius is border-radius + (margin * (1 + (ratio-1)^3)).
- border-box
- 
 Defines the shape enclosed by the outside border edge. This shape follows the normal border radius shaping rules for the outside of the border. 
- padding-box
- 
 Defines the shape enclosed by the outside padding edge. The shape follows the normal border radius shaping rules for the inside of the border. 
- content-box
- 
 Defines the shape enclosed by the outside content edge. Each corner radius of this box is the larger of 0 or border-radius-border-width-padding.
Examples
TODO
Specifications
| Specification | Status | Comment | 
|---|---|---|
| CSS Shapes Module Level 1 The definition of '<shape-box>' in that specification. | Candidate Recommendation | Initial definition. | 
Browser Compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari | 
|---|---|---|---|---|---|
| Basic support | (Yes) | No support | No support | No support | (Yes) | 
| \xx | (Yes) | No support | No support | No support | (Yes) | 
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | No support | No support | No support | (Yes) | 
| \xx | (Yes) | (Yes) | No support | No support | No support | (Yes) |