foundation
CSS Variables (Custom Properties)
Design tokens and live theming with cascading custom properties.
Learning checklist
- Scoping tokens
- Dynamic overrides
- calc() with variables
Definition
Design tokens and live theming with cascading custom properties.
Syntax
Example
Deep dive
Why this matters
Principles, mental models, and debugging clues tailored to the topic.
Visual intuition
Each property is paired with motion or color feedback so you build muscle memory, not just recall syntax.
Copy-ready CSS
Controls emit exact CSS you can copy. Use it as a starter token or paste into DevTools for instant validation.
Performance notes
Learn where reflow, repaint, or compositing occurs so you avoid jank and choose GPU-friendly paths.
Accessibility first
Focus-visible, reduced-motion, and contrast tips are woven into every lab to keep experiences inclusive.
Practice
Try recreating a UI card using this topic. Toggle between dark and light modes to validate token contrast and responsiveness.
Tip: use DevTools overlays (grid/flex) plus the copy CSS button.
Custom Properties
Tweak design tokens as CSS variables. Values cascade automatically and update the live card.
Tokenized UI
:rootGap driven grid
Variables cascade and can be overridden at any scope. Use them to theme components without refactoring markup.
color-mix()
Blend tokens for glass surfaces without maintaining extra swatches.
Related topics
Keep exploring adjacent concepts.