Skills
skills/cometchat/cometchat-skills/cometchat-theming

cometchat-theming

Installation
SKILL.md

Companion skills: cometchat-core covers CSS import placement and the one-import rule; cometchat-customization covers component-level CSS selectors for deeper overrides; cometchat-troubleshooting handles cases where the theme doesn't apply.

Purpose

Teach Claude how to theme CometChat in a v3 (AI-written) integration. Themes are just CSS variable overrides — you write them directly into the project's CSS (or, for Astro, the React island file). Do not use the cometchat apply-theme CLI command — it was a v2 tool that expects a CLI-generated .cometchat/state.json marker that v3 integrations don't create, and it will fail with "No integration found".

1. How CometChat theming works

The CSS variable cascade

CometChat's entire visual identity is driven by 200+ CSS custom properties defined in @cometchat/chat-uikit-react/css-variables.css. This file is imported once at the app root (see cometchat-core). Every <CometChat*> component reads these variables — there is no component-level style-props API for colors, fonts, or spacing.

To override: write CSS rules that set --cometchat-* variables on :root (or a scoped container), after the css-variables.css import. The cascade does the rest — every component picks up the new values automatically.

/* Must appear AFTER the @import of css-variables.css */
:root {
  --cometchat-primary-color: #6C63FF;
  --cometchat-background-color-01: #FFFFFF;
  --cometchat-text-color-primary: #141414;
  --cometchat-font-family: "Inter", sans-serif;
  --cometchat-radius-2: 8px;
}

Dark mode

Two broad strategies — pick based on how the project already handles dark mode.

Strategy A — OS-driven only (simplest). Overrides live inside a @media (prefers-color-scheme: dark) block. The browser swaps themes based on the user's OS preference:

@media (prefers-color-scheme: dark) {
  :root {
    --cometchat-primary-color: #7B73FF;
    --cometchat-background-color-01: #1A1A2E;
    --cometchat-text-color-primary: #E0E0E0;
    /* ... remaining dark overrides ... */
  }
}

Strategy B — App-controlled theme toggle. If the project already has a theme toggle (next-themes, Tailwind dark: prefix, React Context, etc.), wire CometChat's dark mode to the same trigger. The shared trigger is typically a CSS class or data-theme attribute on <html> or <body>. Scope the override to that selector:

/* next-themes default: applies a `.dark` class to <html> */
.dark :root {
  --cometchat-primary-color: #7B73FF;
  --cometchat-background-color-01: #1A1A2E;
  --cometchat-text-color-primary: #E0E0E0;
}

/* OR if the project uses data-theme="dark" on <html> (common with Tailwind CSS v4) */
[data-theme="dark"] :root {
  --cometchat-primary-color: #7B73FF;
  --cometchat-background-color-01: #1A1A2E;
  --cometchat-text-color-primary: #E0E0E0;
}

/* OR for Tailwind's `class` strategy with `darkMode: 'class'` in tailwind.config */
html.dark {
  --cometchat-primary-color: #7B73FF;
  --cometchat-background-color-01: #1A1A2E;
  --cometchat-text-color-primary: #E0E0E0;
}

How to tell which selector the project uses:

Library / setup Selector to target
next-themes (Next.js default) .dark on <html>
Tailwind with darkMode: 'class' html.dark (or .dark on any ancestor)
Tailwind with darkMode: 'media' Matches @media (prefers-color-scheme: dark) — use Strategy A
Tailwind CSS v4 (@custom-variant dark) [data-theme="dark"] by default
Radix UI / shadcn defaults .dark class on <html>
Custom React Context (useTheme() hook) Check what the context writes to the DOM — usually a class on <html> or <body>

Rule: whichever selector is toggled by the app's theme system, use that same selector as the CometChat override's parent. The UI Kit components sit inside the app's DOM, so they inherit whatever variable values are active at the nearest matching scope.

Do not emit both Strategy A and Strategy B in the same stylesheet unless the user explicitly wants "follow OS except when app toggle is set." That's a legitimate pattern but usually over-engineered for a first integration — ship Strategy B alone if the project has a toggle, Strategy A if it doesn't.

Why Astro is different

Astro's client:only="react" islands run in isolation — global stylesheets in .astro layouts do not cascade into them. CSS variable overrides in a global .css file will have no effect on CometChat components. The overrides must live inside the React island .tsx file (typically src/cometchat/ChatApp.tsx), as an inline <style> tag or a CSS import within the component.

2. Use this skill when

The user wants to customize the look and feel of an already-integrated CometChat UI. Trigger phrases:

  • /cometchat theming, /cometchat theme
  • "match my brand colors"
  • "make cometchat dark mode"
  • "change the chat colors"
  • "customize the cometchat ui"
  • "the chat doesn't match my design system"

3. Preconditions

The project must already have a CometChat integration. Check by looking for .cometchat/config.json and the UI Kit dependency:

test -f .cometchat/config.json && cat package.json | grep "@cometchat/chat-uikit-react"

If neither is present, stop and tell the user to run /cometchat to create an integration first. Theming requires the provider + css-variables.css import to already be in place.

4. When to use which path

Situation Path
Complete, opinionated theme fast Path A — Preset
Brand color hex (and optionally font/radius) Path B — Brand color
Existing Tailwind config or CSS custom properties Path C — Design system extraction

5. Preset values

Five built-in presets. All values are in the table below — write them directly into the override CSS; do not try to call a CLI for this.

Preset --cometchat-primary-color --cometchat-text-color-primary --cometchat-background-color-01 --cometchat-font-family --cometchat-radius-2 Dark mode included
slack #611f69 #1d1c1d #ffffff Lato, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif 8px no
whatsapp #25d366 #111b21 #f0f2f5 'Segoe UI', Helvetica, Arial, sans-serif 12px no
imessage #007aff #000000 #ffffff -apple-system, BlinkMacSystemFont, 'SF Pro Text', sans-serif 18px no
discord #5865f2 #dcddde #36393f 'gg sans', 'Noto Sans', Helvetica, Arial, sans-serif 8px yes
notion #2eaadc #37352f #ffffff -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif 6px no

6. Where to write the overrides

Target file is determined by framework in .cometchat/config.json:

Framework Target file
reactjs src/index.css (append :root { ... } block after the existing import)
nextjs src/app/globals.css (App Router) or styles/globals.css (Pages Router)
react-router app/app.css (or src/index.css if you used a Vite-style structure)
astro Inline <style> tag or imported CSS inside src/cometchat/ChatApp.tsx (see section 1 for why)

The override block must be written after the existing @cometchat/chat-uikit-react/css-variables.css import so it takes precedence. If the project imports the CometChat CSS in a TSX file (e.g. src/main.tsx), the override can still live in the adjacent index.css because it appears in the DOM after the JS import resolves.

7. Steps

Step 1 — Ask what theme source to use

If the user already specified a preset name, brand color, or pointed to a design system file, skip to Step 2.

Otherwise use AskUserQuestion:

  • question: "How do you want to theme CometChat?"
  • header: "Theme"
  • multiSelect: false
  • options:
    1. label: "Use a preset", description: "Pick one of: slack, whatsapp, imessage, discord, notion."
    2. label: "Match my brand", description: "Give me your primary brand color (hex). I'll also ask about font and radius."
    3. label: "Match my existing design system", description: "Point me at your tailwind.config.{js,ts} or your CSS variables file. I'll extract the tokens."

Step 2 — Build the override block

Path A — Preset: Look up the preset in section 5's table. Emit a :root { ... } block with those five variables. If the preset's Dark mode included column is "yes" (currently just discord), also emit a @media (prefers-color-scheme: dark) { :root { ... } } block with sensible dark variants (invert background to dark, text to light, keep primary).

Path B — Custom brand color: The user gave you a hex (e.g. #853953). Emit at minimum:

:root {
  --cometchat-primary-color: #853953;
}

Then ask if they want:

  • a matching font family (defaults to the project's existing font stack from body { font-family: ... } in the project's main CSS)
  • a border radius (defaults to 8px)
  • dark mode variants

Step 3 — Read the current CSS file

Read the target file (see section 6) so you can append to it instead of overwriting existing rules. Check the file doesn't already have a --cometchat-primary-color line — if it does, you're updating an earlier theming pass; replace that block rather than duplicating.

Step 4 — Write / update the override block

Use Edit to insert or replace the :root block. Keep it grouped and commented so the user can see where their theme lives:

/* CometChat theme override — edit these to change the chat UI */
:root {
  --cometchat-primary-color: #853953;
  --cometchat-font-family: "Inter", sans-serif;
}

Path C — Design system extraction: Read tailwind.config.{js,ts} (look for theme.colors.primary, theme.colors.background, theme.fontFamily.sans, theme.borderRadius) or the project's root CSS file (look for --primary, --background, etc.). Extract the tokens. Then use Path B's block shape with the extracted values.

Step 5 — Save the choice to config

npx @cometchat/skills-cli config set theme "<preset-or-custom>"

Where <preset-or-custom> is the preset name (e.g. slack) or custom for Path B / Path C.

Step 6 — Tell the user to restart the dev server

The theme is applied. Tell the user:

  1. Restart the dev server (CSS changes need a fresh reload)
  2. Refresh the chat page
  3. Verify the colors match their design

If the theme doesn't appear to apply:

  • Double-check the override block is after the css-variables.css import in the DOM order
  • For Astro: confirm the override is inside the .tsx island, not a global .css file
  • Route to cometchat-troubleshooting for deeper triage.

8. Extended variable list (reference)

Beyond the five "headline" variables in the preset table, common ones worth knowing:

Variable What it controls
--cometchat-primary-color Active message bubble, primary buttons, brand accents
--cometchat-text-color-primary Main body text
--cometchat-text-color-secondary Timestamps, muted labels
--cometchat-background-color-01 Main app background
--cometchat-background-color-02 Panels (conversation list, details sidebar)
--cometchat-background-color-03 Hover / selected states
--cometchat-border-color-light Dividers between rows
--cometchat-font-family All text
--cometchat-radius-2 Medium radius (bubbles, buttons)
--cometchat-radius-3 Larger radius (panels)

For the full 200+ list, query the docs MCP (see below) or read node_modules/@cometchat/chat-uikit-react/dist/styles/css-variables/css-variables.css.

9. Docs MCP contract

The CometChat docs MCP at cometchat-docs is the canonical source for:

  • The full CSS variable list (200+ tokens) with descriptions
  • Component-level styling selectors (.cometchat-message-bubble-outgoing, .cometchat-conversations-header, etc.)
  • Dark mode patterns beyond the simple invert
  • Font / radius / spacing token names

When to use it:

  • Component-level overrides beyond the 10 tokens above (e.g., "make incoming bubbles green" needs a specific selector) — query the docs MCP. Never invent CSS class names from memory.
  • If the docs MCP is not installed and the user asks for this, tell them: "I need the CometChat docs MCP for component-level styling. Install it with claude mcp add --transport http cometchat-docs https://www.cometchat.com/docs/mcp and re-run."

Canonical reference URL: https://www.cometchat.com/docs/ui-kit/react/theme

Hard rules

  • Do NOT call cometchat apply-theme. It's a v2 CLI command that requires a CLI-generated .cometchat/state.json and fails on v3 AI-written integrations. Write CSS directly instead.
  • Never apply theming to a project without an existing CometChat integration (no .cometchat/config.json = no integration).
  • Always write theme overrides after the css-variables.css import.
  • Never invent CSS variable names. Use the preset table (section 5), the common-variables table (section 8), or query the docs MCP.
  • Never edit node_modules or vendor files.
  • Astro is special: theme overrides must live inside the .tsx React island file, not a global .css.
  • Always use npx @cometchat/skills-cli for config saves.
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