The CSS selectors module defines the patterns to select elements to which a set of CSS rules are then applied along with their specificity. The CSS selectors module provides us with more than 60 selectors and five combinators. Other modules provide additional pseudo-class selectors and pseudo-elements.
Pseudo-classes - CSS | MDN
A CSS pseudo-class is a keyword added to a selector that lets you select elements based on information that lies outside of the document tree, such as a specific state of the selected element(s). For example, the pseudo-class :hover can be used to style a button when a user's pointer hovers over it.
The CSS Selection - 2026 Edition - Project Wallace
The CSS Selection shows real-world CSS usage from over 100,000 websites and looks at the most important metrics.
element() CSS function - CSS | MDN
The element() CSS function defines an <image> value generated from an arbitrary HTML element. This image is live, meaning that if the HTML element is changed, the CSS properties using the resulting value are automatically updated.
18 Best CSS Libraries/Frameworks for UI/UX Designs 2024
Here are the 25 best CSS libraries/frameworks for UI/UX designs which make your frontend development more easier and productive with custom features.
7 CSS Tricks That Actually Have Good Browser Support
CSS is filling the gaps with rules. A way to style gaps in grid and flex. | utilitybend
A practical walkthrough of CSS gap decorations: column-rule, row-rule, rule-break, rule-inset, rule-visibility-items, repeat(), and animation.
2026 CSS wishlist – Nathan Knowler
What I’d like to see prioritized for CSS in 2026, how those features will allow us to create better web-based design systems, and how they renew separation of concerns.
@function — Native Custom Functions in CSS
CSS now has user-defined functions. No preprocessor, no JavaScript, but native @function with typed parameters, local variables, and conditional logic built right into your CSS.
CSS Formatter, CSS Beautifier and CSS Minifier Online tool
Best Online CSS Formatter, CSS Beautifier, CSS Minifier, Save and Share CSS. Simple Quick and Fast!
Modern CSS snippets. Every old hack, replaced.
Side-by-side comparisons of outdated CSS techniques and their modern native replacements. Grid, custom properties, nesting, container queries, and more.
Modern CSS snippets. Every old hack, replaced.
Side-by-side comparisons of outdated CSS techniques and their modern native replacements. Grid, custom properties, nesting, container queries, and more.
box-sizing CSS property - CSS | MDN
The box-sizing CSS property sets how the total width and height of an element is calculated.
#10: "Bad at CSS" by Keith Cirkel
schalkneethling/css-benchpress
css-benchpress aims to help developers and tooling authors discover where CSS patterns become performance problems by growing realistic web-platform test cases until measurable regressions appear.