CSS specificity determines which styles are applied when conflicts occur by assigning a weight (a,b,c,d) to selectors, where inline styles (a) > IDs (b) > classes/attributes/pseudo-classes (c) > elements/pseudo-elements (d), and comparisons are made left to right; thus, a single ID selector (0,1,0,0) overrides ten classes (0,0,10,0), and while !important beats all, it should be avoided to maintain cascade integrity and ease debugging.
CSS specificity is a set of rules that determines which CSS style declarations are applied to an element when there are conflicting styles from multiple selectors.

In short: specificity decides which styles win when there's a conflict.
Every CSS selector has a specificity weight. When two or more rules target the same element, the browser applies the one with the higher specificity.

How Specificity Is Calculated
Specificity is often represented as a four-part tuple (a, b, c, d):
-
a → Inline styles (e.g.,
style="..."
) -
b → ID selectors (e.g.,
#header
) -
c → Class selectors, attributes, and pseudo-classes (e.g.,
.btn
,[type="text"]
,:hover
) -
d → Element selectors and pseudo-elements (e.g.,
div
,::before
)
Important: These are not decimal digits. Specificity is compared left to right.

Examples of Specificity Values
Selector | Specificity (a,b,c,d) |
---|---|
p |
(0,0,0,1) |
p:hover |
(0,0,1,1) |
.nav |
(0,0,1,0) |
#header |
(0,1,0,0) |
style="color: red" |
(1,0,0,0) |
div#main .nav a:hover |
(0,1,2,2) |
So, even ten class selectors (0,0,10,0) will lose to a single ID selector (0,1,0,0).
Key Rules to Remember
-
Inline styles have the highest specificity (except
!important
). - ID selectors are stronger than classes.
- Classes, attributes, and pseudo-classes are stronger than elements.
- More specific selectors win over less specific ones.
- Order matters only when specificity is equal — the last rule wins.
What About !important
?
Using !important
overrides all normal specificity, which is why it's generally discouraged. It breaks the natural cascade and makes debugging harder.
But note: !important
on a less specific rule still beats a more specific one without it.
Practical Tips
- Avoid
!important
unless absolutely necessary (e.g., in utility classes or third-party overrides). - Use classes instead of relying on element or ID selectors for better reusability.
- Keep specificity low where possible to make styles easier to override.
Basically, specificity is like a scoring system: the highest score wins, and understanding it helps you write more predictable CSS.
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