Using :nth-child(8) it allows you to specifically choose to change only the 8th element in the parent element
Using the :nth-child(n+6) like this allows you pick :nth-child(6) and above
Using the :nth-child(-n+9) like this allows you pick :nth-child(9) and below
Using this nth-child(n+4):nth-child(-n+8) we can select elements within certain ranges, in this case elements 4-8.
Using this nth-child(n+2):nth-child(odd):nth-child(-n+9) we can select elements within certain ranges (2-9) that are odd-numbered children.
Using this :nth-child(3n+1) would normally highlight children 1, 4, 7 & 10, but by using the :nth-child(even) we filter out the odd numbered children 1 & 7 leaving only the children 4 & 10.