:nth-child

Select the first list item

li:nth-child(1) { }

Selects the second element in a list

li:nth-child(2) {
color: lime;
}

Selects every fourth element among any group of siblings

:nth-child(4n) {
color: lime;
}

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 – 2) { }

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(3n) { }

Select odd elements

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

Select even elements

p:nth-child(even) {
background: blue;
}