CSS custom properties, commonly called CSS variables, are entities defined with a -- prefix (e.g., --primary-color: #4f46e5;). They allow you to store values and reuse them throughout your stylesheet, making theme management, color consistency, and responsive design much easier. Unlike SCSS/LESS variables, CSS variables are dynamic and can be updated at runtime via JavaScript or media queries.

CSS Variables (--name) work natively in browsers, support runtime changes, and cascade like regular CSS properties. SCSS variables ($name) and LESS variables (@name) are preprocessor features — they're compiled at build time and don't exist in the final CSS. Use CSS variables when you need dynamic theming; use preprocessor variables for static design tokens during development. Many modern projects use both: preprocessor variables that compile to CSS custom properties.

Use this tool! Simply add your colors via the color picker, bulk paste, or choose a preset palette. Edit variable names to match your design system (e.g., --color-primary, --color-accent), select your preferred format (CSS/SCSS/LESS), and copy the generated code directly into your stylesheet. The tool automatically saves your palette locally, so you won't lose your work.

A good naming convention avoids describing the actual color (e.g., avoid --color-red) and instead describes the purpose or role of the color. Common patterns: --color-primary, --color-secondary, --color-accent, --color-surface, --color-text, --color-border. For design systems with multiple shades, use numeric scales: --color-primary-50 through --color-primary-900. This makes your palette flexible and semantic.

Absolutely! CSS variables accept any valid CSS color value: HEX (#ff6b6b), RGB (rgb(255,107,107)), HSL (hsl(0,100%,71%)), named colors, and even color functions like oklch(). This tool normalizes all inputs to HEX for consistency, but you can manually edit the output if you prefer a different format. Using HSL with CSS variables is particularly powerful for creating color variations with hsl(var(--h), var(--s), calc(var(--l) + 10%)).

When building a color palette, check contrast ratios between text and background colors. WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text. Tools like the WebAIM Contrast Checker can help. A good practice is to include both light and dark variants of each color in your palette, and to define separate --color-text-on-primary variables that ensure readable text on colored backgrounds.