Hi folks,

The

:nth-child(n)

selector is a pseudo element. which show the position on there parents element.
You can use (even) and (odd) for all even or odd child element.

:nth-child(odd)

For example:-

 tr:nth-child(2n+1)

Represents the odd rows of an HTML table.

 tr:nth-child(odd)

Represents the odd rows of an HTML table.

 tr:nth-child(2n)

Represents the even rows of an HTML table.

 tr:nth-child(even)

Represents the even rows of an HTML table.

 span:nth-child(0n+1)

Represents a span element which is the first child of its parent; this is the same as the :first-child selector.

 span:nth-child(1)

Equivalent to the above.

 span:nth-child(-n+3)

Matches if the element is one of the first three children of its parent and also a span.

n	2n+1	4n+1	4n+4	4n	5n-2	-n+3
0	1	1	4	-	-	3
1	3	5	8	4	3	2
2	5	9	12	8	8	1
3	7	13	16	12	13	-
4	9	17	20	16	18	-
5	11	21	24	20	23	-

As you can see, the matches are exactly the same, no need for the "+3". We can use negative n values, as well as use subtraction in the expressions.

For example:-
4n-1:

(4 x 0) - 1 = -1 = no match
(4 x 1) - 1 = 3 = 3rd Element
(4 x 2) - 1 = 7 = 7th Element