CSS Custom Properties

A guide to building dynamic, themeable stylesheets using CSS custom properties and design token patterns.

Usage

Ask about CSS variables, theming, design tokens, or dynamic styling patterns.

Examples

• "Create a theme system with light and dark modes"
• "How do I update CSS variables with JavaScript?"
• "Build a design token system with custom properties"

Guidelines

• Define global tokens on :root and component tokens on the element
• Use meaningful naming conventions like --color-primary
• Provide fallback values with var(--prop, fallback)
• Leverage cascade and inheritance for theme scoping
• Use custom properties for values that change, not static values