CSS Pseudo Class Selector :only-of-type
Selects elements that are the sole element of their type defined by their containing element
Definition and Notes.
1. CSS Pseudo Class :only-of-type selects and styles elements that are the only child of a type of their parents.
2. The element may have sibling but none of them should be of same type as itself.
3. Eg: p:only-of-type will select <p> element which is of unique type among its siblings.