
:not()
pseudo-class in CSS is a powerful tool that lets you apply styles to elements that do not match a specific selector. It's especially useful when you want to exclude certain elements from a style rule without adding extra classes or modifying your HTML structure.

Basic Usage
<p> You use:not()
by placing another selector inside its parentses. For example:p:not(.special) { color: blue; }<p> This rule will apply blue text to all
<p>
elements except those with the class special
. 
:not()
can't contain another pseudo-class or pseudo-element. So something like :not(:hover)
is allowed, but :not(::before)
is not.Common Use Cases
<p> There are a few everyday situations where:not()
comes in handy: 
- <p> Excluding specific list items:
li:not(.active) { opacity: 0.5; }
<p> This makes inactive list items less prominent. - <p> Styling links except for certain ones:
a:not([href^="https"]) { color: red; }
<p> This changes the color of non-HTTPS links to red. - <p> Avoiding unequal classes in forms:
input:not([type="submit"]) { border: 1px solid #ccc; }
<p> This adds a border to all input fields except submit buttons.
:not()
as long as it's a valid simple selector.Performance and Best Practices
<p> While:not()
is useful, it's worth using it thoughtfully. Here are a few tips:- <p> Avoid overcomplicating selectors:
Using too many nested or chained:not()
selectors can make your CSS harder to read and maintain. - <p> Don't use it for performance gains:
Contrary to some beliefs,:not()
doesn't significantly speed up or slow down rendering in most cases. It's more about convenience than optimization. - <p> Be cautious with broad selectors:
Something like*:not(a)
might seem clever, but it can lead to unexpected styling across your site.
:not()
has no effect if the selector inside it doesn't match anything — so it's best used when you're certain about the elements involved.Nesting and Combining Selectors
<p> You can combine:not()
with other selectors to make more specific rules. For example:div:not(.box):not(.container) { background: yellow; }<p> This targets all
<div>
elements that don't have either the class .box
or .container
.<p> You can also nest :not()
inside other pseudo-classes like :hover
:button:not(.disabled):hover { background: lightblue; }<p> This means the hover effect only applies to buttons that aren't marked as disabled. <p> Basically that's it.
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