add-dark-mode-support

---

name: add-dark-mode-support description: Add dark mode styles to components using Tailwind dark: variant classes. Use when creating new components, adding dark mode support to existing components, or when the user mentions dark mode, theming, or light/dark variants.

Adding Dark Mode Support

This skill guides you through adding dark mode support to components in the CodeCrafters frontend.

How Dark Mode Works

Dark mode is controlled by the DarkModeService (app/services/dark-mode.ts). When enabled:

• The root #application-container div gets the dark class
• Tailwind's dark: variant classes become active (configured as ['variant', ['&:is(.dark *)']])

Route Color Scheme Support

Routes declare their dark mode support via RouteInfoMetadata:

import RouteInfoMetadata, { RouteColorScheme } from 'codecrafters-frontend/utils/route-info-metadata';

export default class MyRoute extends BaseRoute {
  buildRouteInfoMetadata() {
    return new RouteInfoMetadata({ colorScheme: RouteColorScheme.Both });
  }
}

Options:

• RouteColorScheme.Light - Light mode only
• RouteColorScheme.Dark - Dark mode only
• RouteColorScheme.Both - Supports both (user can toggle)

Common Color Patterns

Backgrounds

Light	Dark	Usage
bg-white	dark:bg-gray-925	Cards, containers
bg-white	dark:bg-gray-950	Main backgrounds
bg-gray-50	dark:bg-gray-900	Subtle backgrounds

Borders

Light	Dark	Usage
border-gray-200	dark:border-white/5	Subtle borders
border-gray-200	dark:border-white/10	More visible borders
border-gray-300	dark:border-gray-700	Interactive borders

Text

Light	Dark	Usage
text-gray-900	dark:text-gray-100	Primary headings
text-gray-700	dark:text-gray-200	Secondary headings
text-gray-600	dark:text-gray-300	Body text
text-gray-500	dark:text-gray-400	Muted text
text-gray-400	dark:text-gray-600	Very subtle text

Icons

Light	Dark	Usage
text-gray-300	dark:text-gray-700	Decorative icons
text-gray-400	dark:text-gray-600	Secondary icons

Prose/Typography

For markdown content, use the prose plugin with invert:

<div class="prose dark:prose-invert">
  {{markdown-to-html @content}}
</div>

Implementation Examples

Basic Card Component

<div class="bg-white dark:bg-gray-925 border border-gray-200 dark:border-white/5 rounded-md shadow-xs">
  <div class="text-gray-900 dark:text-gray-100 font-bold">
    {{@title}}
  </div>
  <div class="text-gray-500 dark:text-gray-400 text-sm">
    {{@description}}
  </div>
</div>

Conditional Styling with Dark Variants

When using conditional classes, include dark variants in both branches:

<div class="{{if @isActive
  'border-teal-500 dark:border-teal-700 bg-teal-50 dark:bg-teal-900/30'
  'border-gray-200 dark:border-white/5 bg-white dark:bg-gray-925'
}}">

Interactive Elements with Hover States

<button class="
  bg-white dark:bg-gray-950
  border border-gray-300 dark:border-gray-700
  hover:bg-gray-50 dark:hover:bg-gray-900
  text-gray-700 dark:text-gray-200
">

Color-Coded Alerts

For colored components, use color-specific dark variants:

get containerColorClasses(): string {
  return {
    green: 'bg-green-100/20 dark:bg-green-900/30 border-green-500/60 dark:border-green-500/40',
    blue: 'bg-blue-100/20 dark:bg-blue-900/30 border-blue-500/60 dark:border-blue-500/40',
    red: 'bg-red-100/20 dark:bg-red-900/30 border-red-500/60 dark:border-red-500/40',
  }[this.args.color];
}

Checklist for Adding Dark Mode

When adding dark mode support to a component:

• Add dark:bg-* for all background colors
• Add dark:border-* for all border colors
• Add dark:text-* for all text colors
• Add dark variants to hover/focus states
• Handle conditional classes (both branches need dark variants)
• Use prose dark:prose-invert for markdown content