Represents a CSS pseudo-class such as :active, :focus, or :nthChild(odd).
 Pseudo classes are appended to selectors using the % operator. They are chainable as well meaning
 the following is possible: a %active %hover becomes a:active:hover.
 
Special abbreviations exist such as "odd" for ":nthChild(odd)" and "even" for :nthChild(even).
| Modifiers | Name | Description | 
|---|---|---|
| static class | PseudoClass.StyleGroup | Only here to restrict the DSL so that pseudo-class is used properly. | 
| Type Params | Return Type | Name and description | 
|---|---|---|
|  | PseudoClass | mod(PseudoClass other)Allows chainable pseudo-classes (%active %hover becomes :active:hover). | 
|  | String | toString() | 
Allows chainable pseudo-classes (%active %hover becomes :active:hover).