Specificity.
#footer ais the identifier ( #footer) and element ( a).
, , .
footer a , , a:link, (psuedo), , , .
, , - footer a - , footer a:link, footer a:visited.
, , . , 255 = 1 255 = 1 ID ( ). !important , -, . - , ( , !important) 0,0,0 (, , ).
#footer a 1,0,1.
a:link 0,1,1.
footer a 0,0,2.
. footer a , a:link, 1 1 , . - footer#footer a, footer.bottom a, footer a:link, footer a:visited .. ( HTML). HTML-, psedoclasses :link :visited ( , , psuedo-elements, :before :after count ).
a:link, a:visited a, , , , .
- , , , CSS. , :