DSAI styling system reference, Bootstrap 5 utilities, CSS custom properties (design tokens), cn() utility, dark mode, and token pipeline. Replaces the old tailwindcss skill. Use this skill when generating or modifying styles, classNames, or theme configuration in DSAI consumer applications.

DSAI Styling System

Architecture

DSAI uses Bootstrap 5 as the base CSS framework, with design tokens (CSS custom properties) providing the customization layer.

NO Tailwind CSS. Never use Tailwind utility classes in DSAI projects.

Token Pipeline

DTCG JSON tokens (src/collections/) are compiled via dsai tokens build into multiple output formats:

Output File	Purpose
`src/generated/css/tokens.css`	Light theme tokens (`:root` selector, `--dsai-*` prefix)
`src/generated/css/tokens-dark.css`	Dark theme tokens (`[data-dsai-theme="dark"]` selector)
`src/generated/css/dsai-theme-bs.css`	Bootstrap compiled with DSAI token overrides
`src/generated/scss/_variables.scss`	Sass variables for build-time usage
`src/generated/js/tokens.js`	JavaScript token module
`src/generated/ts/tokens.d.ts`	TypeScript type declarations
`src/generated/json/tokens.json`	Raw JSON token map

After editing any token JSON in src/collections/, run:

dsai tokens build

CSS Import Order

CRITICAL — imports in main.tsx must follow this exact order:

import '../generated/css/dsai-theme-bs.css';    // 1. Bootstrap + DSAI token overrides
import '../generated/css/tokens.css';            // 2. Light theme CSS custom properties
import '../generated/css/tokens-dark.css';       // 3. Dark theme CSS custom properties
import './index.css';                            // 4. App base styles
import './custom.css';                           // 5. App overrides

Changing this order will break theme resolution and specificity.

CSS Custom Properties

All design tokens are exposed as CSS custom properties prefixed with --dsai-:

var(--dsai-color-primary)
var(--dsai-spacing-3)
var(--dsai-font-size-base)
var(--dsai-shadow-lg)
var(--dsai-border-radius)

Use these for any value not covered by a Bootstrap utility class.

Bootstrap 5 Utility Classes

Use Bootstrap utilities — not Tailwind classes.

Layout

Category	Classes
Display	`d-flex`, `d-grid`, `d-block`, `d-none`, `d-inline`
Flex direction	`flex-row`, `flex-column`, `flex-wrap`
Flex alignment	`justify-content-center`, `align-items-center`
Gap	`gap-1` through `gap-5`
Position	`position-relative`, `position-absolute`, `position-fixed`, `position-sticky`

Spacing

Margin: m-0 through m-5, directional: mt-, mb-, ms-, me-, mx-, my-

Padding: p-0 through p-5, directional: pt-, pb-, ps-, pe-, px-, py-

Typography

Category	Classes
Alignment	`text-center`, `text-start`, `text-end`
Color	`text-body-secondary`, `text-muted`
Weight	`fw-bold`, `fw-semibold`
Size	`fs-1` through `fs-6`

Sizing

w-100, w-75, w-50, w-25, h-100, min-vh-100

Visibility & Overflow

visually-hidden (NOT sr-only), overflow-hidden

Borders

border, border-0, rounded, rounded-circle

Backgrounds

bg-primary, bg-secondary, bg-body-secondary, bg-body-tertiary

Semantic Colors

text-primary, text-secondary, text-success, text-danger, text-warning, text-info

cn() Utility

cn() is a simple filter-and-join helper. It is not tailwind-merge and not clsx.

function cn(...classes: (string | boolean | undefined | null)[]): string {
  return classes.filter(Boolean).join(' ');
}

Usage

cn('btn', `btn-${variant}`, size === 'lg' && 'btn-lg', disabled && 'disabled', className)

Important: cn() performs no conflict resolution — it only concatenates truthy values. Class order matters for CSS specificity.

Using Tokens in Components

Combine cn(), Bootstrap utilities, and --dsai-* tokens in component TSX:

import { forwardRef } from 'react';
import { cn } from '@/utils/cn';
import type { AlertProps } from './Alert.types';

export const Alert = forwardRef<HTMLDivElement, AlertProps>(
  function Alert({ variant = 'info', dismissible, className, children, ...props }, ref) {
    return (
      <div
        ref={ref}
        className={cn(
          'alert',                          // Bootstrap base class
          `alert-${variant}`,               // Bootstrap variant
          dismissible && 'alert-dismissible fade show',
          className                         // Consumer overrides
        )}
        role="alert"
        style={{
          borderRadius: 'var(--dsai-border-radius)',       // DSAI token
          padding: 'var(--dsai-spacing-3) var(--dsai-spacing-4)',  // DSAI tokens
        }}
        {...props}
      >
        {children}
      </div>
    );
  }
);
Alert.displayName = 'Alert';

When to Use What

Need	Use	Example
Layout, spacing, display	Bootstrap utility classes	`d-flex gap-3 p-3`
Component variants	Bootstrap component classes via `cn()`	`cn('btn', \`btn-${variant}`)`
Brand colors, custom sizes, shadows	`--dsai-*` CSS custom properties	`var(--dsai-color-primary)`
Conditional classes	`cn()` with boolean expressions	`cn('btn', loading && 'disabled')`
Theme-aware values	Tokens (auto-switch light/dark)	`var(--dsai-bg-surface)`

Rule of thumb: Use Bootstrap utilities for standard layout. Use --dsai-* tokens for brand/theme values that Bootstrap doesn't cover.

Dark Mode in Practice

Toggle Theme

import { useDarkMode } from '@/hooks/useDarkMode';

function ThemeToggle() {
  const { isDark, toggle } = useDarkMode();

  return (
    <Button
      variant={isDark ? 'light' : 'dark'}
      onClick={toggle}
      aria-label={`Switch to ${isDark ? 'light' : 'dark'} mode`}
    >
      {isDark ? 'light' : 'dark'}
    </Button>
  );
}

Theme-Aware Component Styles

Tokens automatically resolve to the correct value based on the active theme:

/* No conditional logic needed — tokens handle it */
.custom-card {
  background: var(--dsai-bg-surface);           /* white in light, dark gray in dark */
  color: var(--dsai-color-body);                /* dark text in light, light text in dark */
  border: 1px solid var(--dsai-border-color);   /* adapts per theme */
  box-shadow: var(--dsai-shadow-sm);            /* adapts per theme */
}

Dark Mode

Enabling Dark Mode

Both data attributes must be set on <html> for theming to work:

document.documentElement.setAttribute('data-dsai-theme', 'dark');
document.documentElement.setAttribute('data-bs-theme', 'dark');

CSS Selectors

Theme	Selector
Light (default)	`:root`
Dark	`[data-dsai-theme="dark"]`
Auto-detect	`prefers-color-scheme: dark` media query

Postprocessing

The token build pipeline replaces data-bs-theme with data-dsai-theme in generated CSS files. DSAI controls theming independently while Bootstrap continues to work.

Design Token Format (DTCG)

Token JSON files in src/collections/ follow the Design Token Community Group format:

{
  "color": {
    "blue": {
      "500": {
        "$value": "#0a58ca",
        "$type": "color",
        "$description": "Base primary brand color",
        "$extensions": {
          "platform": {
            "scssVariableName": "$color-blue-500",
            "bootstrapVersion": "5.3"
          }
        }
      }
    }
  }
}

Token Collections

Collection	Contents
`color/`	primitive, semantic, background, component, neutral, opacity (all with `-dark` variants)
`typography/`	sizes, weights, line heights, letter spacing, headings, display
`spacing/`	0–11 scale: 0px, 4px, 8px, 16px, 24px, 48px, 64px, 80px, 96px, 128px, 160px
`border/`	width, radius
`shadow/`	sm, default, lg
`layout/`	container, grid breakpoints

Color Palettes

Primitive colors: blue, indigo, purple, pink, red, orange, yellow, green, teal, cyan — each with shades 50–950 (13 steps).

Semantic colors: primary, secondary, success, danger, warning, info, light, dark.

Configuration — dsai.config.mjs

import { defineConfig } from '@dsai-io/tools';

export default defineConfig({
  tokens: {
    source: 'theme',
    sourceDir: './src/figma-exports',
    collectionsDir: './src',
    outputDir: './src/generated',
    prefix: '--dsai-',
    formats: ['css', 'scss', 'js', 'ts', 'json'],
    scss: {
      themeEntry: 'src/scss/dsai-theme-bs.scss',
      framework: 'bootstrap',
    },
    themes: {
      enabled: true,
      default: 'light',
      definitions: {
        light: { isDefault: true, selector: ':root' },
        dark: {
          selector: '[data-dsai-theme="dark"]',
          mediaQuery: '(prefers-color-scheme: dark)',
        },
      },
    },
    aliases: {
      importAlias: '@/',
      ui: 'src/client/components/ui',
      hooks: 'src/client/hooks',
      utils: 'src/client/lib/utils',
    },
  },
});

Critical Rules

NEVER use Tailwind utility classes (no flex, no Tailwind-style gap-3, no bg-blue-500).
USE Bootstrap utility classes (d-flex, gap-3, bg-primary, text-body-secondary).
NEVER hardcode colors — use var(--dsai-*) custom properties or Bootstrap semantic classes.
NEVER hardcode spacing — use Bootstrap spacing utilities or token values.
CSS import order in main.tsx must be maintained exactly as documented.
Both data-dsai-theme and data-bs-theme attributes are required for theme switching.
Token edits require dsai tokens build to regenerate outputs.
Use visually-hidden (Bootstrap), not sr-only (Tailwind).
cn() is simple — no conflict resolution, just concatenation. Class order matters for specificity.

dsai-styling