Specificity is measurement of the weight
associated with a CSS rule. This is one of the features that makes cascading stylesheets so powerful. If you find yourself attaching classes and not seeing the styles applied, then it is probably a specificity issue. In short, styles applied to id
attributes weigh more than those applied to class
attributes, which weigh more than those applied to tags. Specificity becomes complicated when considering CSS rules with multiple id
, class
, or tag
declarations. No matter how many tag
declarations in a rule, they will never outweigh a class
declaration, and the same is true that many class
declarations can never outweigh an id
.
Anyway, this is described in full by an article on Smashing Magazine: