CSS Glossary
Every CSS concept explained in plain English with code examples and common mistakes. Pick a term below to learn it in under 5 minutes.
Layout
Flexbox
A one-dimensional layout model that distributes space among items in a container along a single axis (row or column).
Learn more →CSS Grid
A two-dimensional layout system that lets you control both rows and columns simultaneously for complex page layouts.
Learn more →Responsive Design
A design approach where layouts adapt to different screen sizes using media queries, flexible grids, and fluid images.
Learn more →Box Model & Visual
Cascade & Inheritance
CSS Specificity
The algorithm browsers use to decide which CSS rule wins when multiple rules target the same element.
Learn more →CSS Cascade
The process browsers follow to combine stylesheets and resolve conflicts using origin, specificity, and source order.
Learn more →CSS Reset
A stylesheet that removes inconsistent default browser styles so every project starts from a clean, predictable baseline.
Learn more →Stacking & Positioning
Why Learn CSS Fundamentals?
Frameworks come and go, but the CSS specification is the foundation everything else is built on. Understanding concepts like the cascade, specificity, and the box model makes you faster at debugging, better at reading other people's code, and more confident when you need to step outside a component library.
Each glossary entry on this page gives you a one-sentence definition, a real-world analogy, working code you can copy, and the most common mistakes developers make -- all in a 3-minute read.