In an HTML document, CSS class selectors match an element based on the contents of the element's class attribute. The class attribute is defined as a space-separated list of items, and one of those items must match exactly the class name given in the selector.
Syntax
.classname { style properties }
Note this is equivalent to the following attribute selector:
[class~=classname] { style properties }
Example
CSS
span.classy {
  background-color: DodgerBlue;
}
HTML
<span class="classy">Here's a span with some text.</span> <span>Here's another.</span>
Specifications
| Specification | Status | Comment | 
|---|---|---|
| Selectors Level 4 The definition of 'class selectors' in that specification. | Working Draft | No changes | 
| Selectors Level 3 The definition of 'class selectors' in that specification. | Recommendation | |
| CSS Level 2 (Revision 1) The definition of 'child selectors' in that specification. | Recommendation | |
| CSS Level 1 The definition of 'child selectors' in that specification. | Recommendation | Initial definition | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari | 
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | 
| Feature | Android | Chrome for Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|---|
| Basic support | ? | ? | (Yes) | ? | ? | ? | ? | 
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                       Last updated by:
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