Generate CSS Custom Properties from Any Color Convert a set of colors into CSS custom properties (variables).

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Color to CSS Variables

Convert a set of colors into CSS custom properties (variables).

Add Colors

Add colors with custom variable names using color pickers.

Choose Format

Select output format: HEX, RGB, or HSL.

Copy CSS

Copy the generated :root CSS custom properties block.

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What Is Color to CSS Variables?

The Color to CSS Variables generator converts a collection of named colors into CSS custom properties (:root variables) ready to paste into your stylesheets. You can add any number of colors, give each a semantic variable name (like "primary," "secondary," "accent"), and choose the output format: HEX for simplicity, RGB comma-separated for rgba() flexibility, or HSL comma-separated for easy runtime manipulation. CSS custom properties are the foundation of modern theming systems, enabling dark mode, brand theming, and dynamic color updates. This tool generates the boilerplate :root { --variable: value; } block so you can quickly set up a color system. The live preview shows all your colors together as a palette strip.

Why Use Color to CSS Variables?

Add unlimited colors with custom variable names
Three output formats: HEX, RGB, or HSL
Generates clean :root { } CSS block
Live palette strip preview
Foundation for CSS theming systems

Common Use Cases

CSS Theming

Set up CSS custom properties for light/dark mode theming.

Design Tokens

Convert design system tokens to CSS variables.

Brand Colors

Create a reusable CSS variable set for brand colors.

Component Libraries

Define customizable color variables for CSS component libraries.

Technical Guide

CSS custom properties (var(--name)) are defined in a :root selector for global scope. HEX format stores the complete color value: --primary: #3B82F6. RGB comma-separated format stores channels: --primary: 59, 130, 246, which can be used as rgb(var(--primary)) or rgba(var(--primary), 0.5) for flexible opacity. HSL format stores: --primary: 217, 91%, 60%, usable as hsl(var(--primary)). The RGB and HSL formats are more flexible because they allow adding opacity at the point of use without redefining the variable. CSS custom properties are inherited by all child elements and can be overridden in media queries or class selectors for theme switching. They are supported in all modern browsers and cascade like regular CSS properties.

Tips & Best Practices

1
Use semantic names like --primary, --secondary instead of --blue, --red for flexibility
2
RGB format is most flexible: rgba(var(--primary), 0.5) gives you opacity control
3
HSL format lets you derive variations: hsl(var(--primary-h), var(--primary-s), 90%)
4
Override variables in media queries for dark mode: @media (prefers-color-scheme: dark) { :root { ... } }
5
Keep your variable count manageable — most systems need 5-10 color variables

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Frequently Asked Questions

Q What format should I use for CSS variables?

HEX for simplicity and readability. RGB if you need opacity control via rgba(var(...), alpha). HSL if you want to derive color variations by adjusting individual components.

Q What browsers support CSS custom properties?

All modern browsers since 2016: Chrome 49+, Firefox 31+, Safari 9.1+, Edge 15+. Not supported in IE11.

Q Can I use variables for dark mode?

Absolutely. Define light mode values in :root, then override in @media (prefers-color-scheme: dark) { :root { ... } } or on a .dark class.

About This Tool

Color to CSS Variables is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.