Declare scoped CSS variables (--primary-bg), implement dark/light theme cascades, and manage design system tokens.
CSS Custom Properties Architecture
### CSS Variables Syntax
CSS variables are defined starting with double dashes (`--color-primary: #3b82f6;`) inside selector blocks (`:root` for global scope) and consumed via `var(--color-primary)`.
💻 Ready to test your knowledge with code?
Solve the hands-on coding exercise in the interactive code editor.