The priority of the rules depends on their relative specificity. Specificity is computed as
three numbers,
a
-
b
-
c
(in a number system with a large base). The number of ID building
blocks in the selector gives the first number
a
, the number of classes, pseudo-classes and attributes gives
b
, and the number of element types gives
c
.
The examples in the following table are in
priority order, with the most specific first.
Priority Order Example
|
Selector
|
Specificity
|
|---|---|
|
#title > #author.full
|
“2-1-0”
|
|
#title
|
“1-0-0”
|
|
P.intro P.citation
|
“0-2-2”
|
|
UL OL LI.red
|
“0-1-3”
|
When two rules give the same specificity
number, the order of appearance gives the priority (the last seen
overrides previous rules).
Priority is used as follows: first the
declarations of all rules that match the same objects are merged,
and then the priority is applied only if there is a conflict (same
key value) within the merged declaration block.