Ignite UI for React — Theming Skill

Prerequisites

• A React project with igniteui-react installed
• A theme CSS file imported in your entry point (see igniteui-react-components)
• The Ignite UI Theming MCP server (igniteui-theming)

AGENT INSTRUCTION — MCP Server Setup (REQUIRED)

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Before using any theming tools, you MUST verify the MCP server is available by calling detect_platform. If the tool is not available or the call fails, you MUST automatically configure it by following the setup process steps described below.

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After writing the file, inform the user that the MCP server has been configured and they may need to reload the editor for the tools to activate. Start the MCP server and wait for that MCP server to start before continuing the theming related work. Do NOT skip this step or ask the user to do it manually.

Description

This skill teaches AI agents how to theme Ignite UI for React applications. One approach is supported:

• CSS custom properties — works in any project without additional build tooling

The skill also covers component-level theming, layout controls (spacing, sizing, roundness), and how to use the Ignite UI Theming MCP server for AI-assisted code generation — all in a React application context.

Example Usage

• "How do I change the primary color in my Ignite UI React app?"
• "Apply a dark theme to my React app"
• "Customize the grid header colors"
• "How do I scope a theme to a specific section of my React app?"
• "Set up Material Design theming for Ignite UI components"

Setting Up the Theming MCP Server

Full setup instructions for VS Code, Cursor, Claude Desktop, and JetBrains IDEs are in [`reference/MCP-SERVER.md`](./reference/MCP-SERVER.md). Read that file for editor-specific configuration steps and verification.

Related Skills

• igniteui-react-components — Choose the right components and set up your React project
• igniteui-react-optimize-bundle-size — Optimize after theming

When to Use

• Applying custom brand colors or a dark theme to an Ignite UI React app
• Overriding individual component styles (e.g., grid header color, button appearance)
• Switching between light and dark mode in a React app
• Scoping different themes to different sections of a React app
• Setting up the Ignite UI Theming MCP server for AI-assisted theming

Content Guide

This skill is organized into focused sections. Refer to the appropriate file for detailed instructions:

Quick Start

1. Import a Pre-built Theme (REQUIRED)

// main.tsx
import 'igniteui-webcomponents/themes/light/bootstrap.css';

For grids, also import:

import 'igniteui-react-grids/grids/themes/light/bootstrap.css';

2. Override with CSS Custom Properties

/* src/index.css */
:root {
  --ig-primary-h: 211deg;
  --ig-primary-s: 100%;
  --ig-primary-l: 50%;
}

// main.tsx
import 'igniteui-webcomponents/themes/light/bootstrap.css'; // Theme first
import './index.css'; // Overrides second

Theming Architecture

The Ignite UI theming system is built on four pillars:

Design Systems

• Bootstrap (default), Material, Fluent, Indigo
• Each has light and dark variants

Key Concepts

CSS Custom Properties

Override tokens in your CSS:

:root { --ig-primary-h: 211deg; }
.admin-panel { --ig-primary-h: 260deg; }

Component-Level Theming

Target web component tag names in CSS:

igc-button { --ig-button-foreground: var(--ig-secondary-500); }

CSS ::part() Selectors

igc-input::part(input) { font-size: 1.1rem; }

Layout Controls

:root {
  --ig-size: 2;          /* 1=small, 2=medium, 3=large */
  --ig-spacing: 1;       /* 0.5=compact, 1=default, 2=spacious */
  --ig-radius-factor: 1; /* 0=square, 1=max radius */
}

Light/Dark Switching

See CSS-THEMING.md for approaches: class toggle, media query, or stylesheet swap.

Best Practices

1. Import theme CSS first, then your custom overrides
2. Use palette tokens (var(--ig-primary-500)) for all colors — never hardcode hex values
3. Use CSS custom properties on `:root` for global theme adjustments
4. Scope overrides with CSS classes for different sections
5. Use `::part()` selectors to style shadow DOM internals
6. In CSS selectors, use web component tag names (igc-button), not React names (IgrButton)
7. Test both light and dark themes
8. Use the MCP server for AI-assisted theme generation when available

Key Rules

1. Never overwrite existing files directly — propose theme code as an update for user review
2. Always call `detect_platform` first when using MCP tools
3. Always call `get_component_design_tokens` before `create_component_theme`
4. Palette shades: 50 = lightest, 900 = darkest
5. Surface color must match variant — light color for light, dark for dark
6. Never hardcode colors after palette generation

Additional Resources

• Ignite UI for React — Themes Overview
• igniteui-theming npm package
• CSS Custom Properties on MDN
• CSS ::part() on MDN