First-child background color is yellow. The headline is the first child of its parent (body). This paragraph is not.
This paragraph is also not the first child of its parent.
This paragraph is the first child of its parent (div).
This paragraph is not the first child of its parent.
This paragraph is the last child of its parent, background-color pink, margin-bottom 30px.
Note: For :first-child or :last-child to work in IE8 and earlier, a !DOCTYPE must be declared.