Can I use any selector?

Yes, change the selector field from :root to any class or element selector.

Do variable names need the -- prefix?

Yes, CSS custom properties always start with two dashes.

Can I add as many tokens as I like?

Yes, use Add token to append new variables.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

CSS Variables Theme Builder

Build a custom property theme with a live preview.

Support

Works Offline

Privacy First

No Login

No API

Tokens

Selector

Preview

Themed element

Uses your CSS variables live.

Generated CSS

:root {
  --color-primary: #6366f1;
  --color-bg: #0f172a;
  --color-text: #f8fafc;
  --radius: 12px;
  --spacing: 16px;
}

About the CSS Variables Theme Builder

Define CSS custom properties (variables) with any selector, edit their values, and see them applied live to a themed preview element. Add or remove tokens freely and copy the generated CSS block.

Examples

Color tokens

--color-primary: #6366f1

Output

:root { --color-primary: #6366f1; }

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

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Version 1.0.0 · Updated 2026-08-07 · Runs entirely in your browser