CSS Selector Specificity and Precedence

When multiple CSS selectors apply to a single element, the browser must determine which selector takes precedence. This is known as the selector specificity.

Rules for Determining Selector Specificity:

1. !important and Inline Styles Override:

   • Styles declared with the !important flag or inline using the style attribute have the highest priority.

2. Specificity:

   • The specificity of a selector is determined by the number and type of its components:

     • #id has higher specificity than .classname
     • .classname has higher specificity than tagname

3. Last Rule Prevails:

   • If two selectors have the same specificity, the one declared last in the CSS file takes precedence.

Example:

Consider the following CSS rules:

body { font-size: 14px; }
#header { font-size: 16px; }

For the

element within the , both rules apply. However, since the #header selector has higher specificity (#id > tagname), its font-size value of 16px will be applied to the

element.

Note:

It is not uncommon to have multiple rules targeting the same element with different levels of specificity. This can be used to refine styles for specific cases or override global rules for specific instances.