Specify a background color for every p element that is the second child of its parent:
The :nth-child(n) selector matches every element that is the nth child, regardless of type, of its parent.
n can be a number, a keyword, or a formula.
Tip: Look at the :nth-of-type() selector to select the element that is the nth child, of a particular type, of its parent.
The :nth-child() selector is supported in all major browsers, except IE8 and earlier.
Odd and even are keywords that can be used to match child elements whose index is odd or even (the index the first child is 1).
Here, we specify two different background colors for odd and even p elements:
Using a formula (an + b). Description: a represents a cycle size, n is a counter (starts at 0), and b is an offset value.
Here, we specify a background color for all p elements whose index is a multiple of 3:
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