Understanding CSS Pseudo-Classes
A CSS pseudo-class is a keyword added to selectors that specifies a special state of the selected elements. Pseudo-classes allow you to style elements based on their state, position, or relation to other elements, without needing to add extra classes in HTML.
Common Pseudo-Classes
- `:hover` – Styles an element when the user hovers over it with a mouse.
 - `:focus` – Styles an element when it receives focus (e.g., input fields).
 - `:active` – Styles an element during activation (e.g., when a button is clicked).
 - `:first-child` / `:last-child` – Targets elements based on their position among siblings.
 - `:nth-child(n)` – Styles elements based on a numeric pattern among siblings.
 - `:not(selector)` – Selects elements that do not match the given selector.
 - `:disabled` / `:checked` – Styles form elements based on their state.
 
Example: Using Pseudo-Classes
In this example, pseudo-classes are used to style buttons on hover, input fields on focus, and list items based on their position among siblings.
Best Practices
- Use pseudo-classes to reduce the need for extra classes in HTML for styling dynamic states.
 - Combine pseudo-classes with pseudo-elements (`::before`, `::after`) for more complex designs.
 - Be mindful of accessibility; for example, `:hover` effects should not be the only way to convey important information.
 - Test pseudo-class styling across different browsers to ensure consistent behavior.