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Frontend Glossary

Frontend engineering · Basics

Cascading Style Sheets

Also called: CSS, Stylesheet, Styles

The styling language that controls how a web page looks. It handles color, fonts, spacing, layout, and animation, and turns the bare HTML frame into something nice and usable.

In detail

If HTML is the frame, CSS is the interior design: what color the walls are, where the furniture goes, how big the windows are. CSS uses "selectors" to pick elements, then sets properties on them, like color, margin, or display: flex.

"Cascading" means that when several style rules apply to the same element, the browser decides which one wins based on priority and order. A common beginner problem is "I changed the style and nothing happened." Most of the time, it's being overridden by another, more specific rule. You can see which rule is crossed out in developer tools.

Projects today often use Tailwind CSS, CSS Modules, and similar approaches. They all turn into plain CSS in the end.

Developer info
Term ID
eng-css
DOM selectors
No DOM cues. This concept isn't detected directly on a page.
Priority
1 · when several match at the same level, the higher priority wins
Version
v1 · updated Sep 29, 2026