css pseudo selectors where code example

Example 1: css pseudo elements

h2::first-letter {}
p::first-line {}
p::selection {background-color: red;}
::after / ::before

Example 2: css pseudo classes

button/anchor:hover / :active / :checked
:nth-of-type(3) // select the third element
:nth-of-type(3n) // select an element every three