Check out example codes for "nth-child in css". It will help you in understanding the concepts better.

Code Example 1

:nth-child()

Code Example 2

:nth-child(3) { //the number is the child number you are targeting
	//styles here 
}

Code Example 3

/* Select the first list item */
li:nth-child(1) { }

/* Select the 5th list item */
li:nth-child(5) { }

/* Select every other list item starting with first */
li:nth-child(odd) { }

/* Select every 3rd list item starting with first */
li:nth-child(3n) { }

/* Select every 3rd list item starting with 2nd */
li:nth-child(3n - 1) { }

/* Select every 3rd child item, as long as it has class "el" */
.el:nth-child(3) { }

Code Example 4

p:nth-child(2)
 	{     
 		background: red;
 	}

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