21st-design-sync

Original：🇺🇸 English

Translated

Look at the current project's design (its shadcn / Tailwind CSS variables and color tokens) and publish it to the 21st.dev community as a shareable theme, using `21st publish-theme`. Use when the user says "publish my theme", "share our design as a 21st theme", "sync my design to 21st", "turn my globals.css into a theme", "залей наш дизайн темой", "опубликуй тему". This is the 21st equivalent of design-sync: it reads the project's design tokens and syncs them into the public theme library.

3installs

Source21st-dev/skill

Added on2026-08-14

NPX Install

npx skill4agent add 21st-dev/skill 21st-design-sync

SKILL.md Content

View Translation Comparison →

21st Design Sync — publish your project's design as a theme

Take the design a project already ships (its light + dark CSS variables) and publish it to the public 21st.dev theme library so anyone can preview, bookmark, and apply it. Under the hood this is one CLI call:

21st publish-theme <file.css> --name "…"

.

Pre-flight (always)

Auth needs a real API key.
```
publish-theme
```
is a management endpoint: it accepts a
```
21st_sk_…
```
key only, not a
```
21st login
```
session token. Get one at https://21st.dev/mcp (or https://21st.dev/settings/api-keys) and pass it via
```
--api-key 21st_sk_…
```
or the
```
TWENTYFIRST_TOKEN
```
/
```
API_KEY_21ST
```
env var. If the user has no key, point them there — don't try to mint one.
The CLI is the unified
```
@21st-dev/cli
```
(bin
```
21st
```
). Use
```
npx @21st-dev/cli
```
if it isn't installed.
Publishing is public and outward-facing. A published theme is immediately
```
is_public
```
in the community library (there is no unlisted/private option for themes). Confirm with the user before publishing.

Step 1 — Find the project's design tokens

Locate the file that defines the shadcn/Tailwind theme variables. Check, in order:

```
app/globals.css
```
,
```
src/app/globals.css
```

src/index.css

,

styles/globals.css

,

app/styles/globals.css

You're looking for a

:root { … }

block of CSS custom properties (

--background

,

--foreground

,

--card

,

--primary

,

--secondary

,

--muted

,

--accent

,

--destructive

,

--border

,

--input

,

--ring

, the

--chart-*

/

--sidebar-*

tokens,

--radius

) and a matching

.dark { … }

block. Values may be

hsl(...)

,

oklch(...)

, hex, or raw channels — keep them exactly as the project wrote them.

Tailwind v4 projects usually keep the same

:root

/

.dark

blocks plus an

@theme inline

mapping; you only need the

:root

and

.dark

token values, not the

@theme

mapping.

Step 2 — Assemble a valid theme CSS file

The publish endpoint parses

--name: value;

pairs out of a

:root { … }

block and a

.dark { … }

block, and requires both to be non-empty. So the file you publish must contain both.

Copy the project's
```
:root
```
and
```
.dark
```
blocks into a standalone file (e.g.
```
project-theme.css
```
). Nothing else is required.
If the project has only a light
:root
and no
.dark
(or an empty one), generate a dark variant before publishing — don't ship a theme with an empty dark mode. Reuse the
```
add-dark-mode
```
/
```
oklch-skill
```
approach: invert lightness while preserving hue/chroma so the dark set stays on-brand. Keep the same token names.
Keep the token names shadcn-standard so the theme previews correctly on the card and applies cleanly for others.

Minimal shape:

css

:root {
  --background: 0 0% 100%;
  --foreground: 240 10% 4%;
  --primary: 240 6% 10%;
  /* …the rest of the project's light tokens… */
  --radius: 0.5rem;
}
.dark {
  --background: 240 10% 4%;
  --foreground: 0 0% 98%;
  --primary: 0 0% 98%;
  /* …the rest of the project's dark tokens… */
}

Step 3 — Name & tag it

Name (required, ≤ 50 chars): infer from the project — the product/brand name from
```
package.json
```
, the repo, or the site title. Ask the user if it's ambiguous.
Tags (optional): a few descriptors that match how people browse themes, e.g.
```
dark
```
,
```
minimal
```
,
```
neutral
```
,
```
vibrant
```
,
```
saas
```
. Pass comma-separated.

Step 4 — Publish

bash

21st publish-theme ./project-theme.css \
  --name "Acme" \
  --tags dark,minimal \
  --api-key 21st_sk_…            # or set TWENTYFIRST_TOKEN

The command prints the live theme URL (

https://21st.dev/community/themes/<slug>

). Share it with the user.

Updating vs re-publishing

Each
publish-theme
creates a NEW theme (there's no upsert-by-slug like components have). Running it twice = two themes in the library.
To change name/tags/visibility on an existing theme, edit it in place:
```
21st edit <theme-id> --type theme [--name "…"] [--tags a,b]
```
.
To change the colors, publish a fresh file and remove the old one:
```
21st delete <theme-id> --type theme --yes
```
(soft-unpublish, reversible).

When NOT to use this

Syncing a component library to a Claude Design project → that's the built-in
```
/design-sync
```
skill, a different destination.
Publishing a component (not a color theme) → use
```
21st-registry
```
.