that's the solution.
but we must carefull when placing the css, because the order would be affected to display.
we must place css in order:
a.link: {......}
a.active: {......}
a.visited: {......}
a.hover: {......}
otherwise we may have problem when we want to make visited style equal to link style. For example, if we want link color = blue, visited color = blue, and hover color = red.