Stu — Tailwind Utility CSS Transformer

Stu downloads the Tailwind v4 standalone CLI, discovers all available utility classes from the Tailwind source, and transforms them into a standalone CSS file with plain px sizes and #hex colors. No Node.js required.

Designed for simpler HTML templating environments that support Tailwind class names but not the full Tailwind build pipeline — for example, email templates, PDF renderers, or embedded HTML editors that need computed CSS values.

Installation

Add the NuGet package to your project:

dotnet add package Stu

This adds an MSBuild integration that automatically generates the Tailwind utility CSS file as part of your build or publish pipeline.

MSBuild configuration

Configure Stu in your .csproj file:

<PropertyGroup>
  <!-- Where to write the generated CSS (relative to project root) -->
  <StuOutput>wwwroot/css/tailwind-utilities.css</StuOutput>

  <!-- When to run: Build, Publish, or Both (default: Publish) -->
  <StuRunOn>Publish</StuRunOn>

  <!-- Limit to specific color families (default: all) -->
  <StuColors>gray,red,green,blue</StuColors>

  <!-- Base font size for rem-to-px conversion (default: 16) -->
  <StuBaseFontSize>16</StuBaseFontSize>

  <!-- Minify the output (default: false) -->
  <StuMinify>false</StuMinify>

  <!-- Force re-download of the Tailwind CLI (default: false) -->
  <StuForceDownload>false</StuForceDownload>
</PropertyGroup>

With StuRunOn set to Publish (the default), the CSS file is generated during dotnet publish. Set it to Build to regenerate on every build, or Both for both.

You can also trigger it manually:

dotnet msbuild -t:StuTransform

MSBuild properties

Property	Default	Description
StuOutput	tailwind-utilities.css	Output CSS file path
StuColors	all	Comma-separated color families, or all
StuBaseFontSize	16	Base font size in px for rem and line-height conversion
StuMinify	false	Minify the output CSS
StuRunOn	Publish	When to run: Build, Publish, or Both
StuForceDownload	false	Force re-download of Tailwind CLI
StuCacheDir	~/.cache/tailwind	Tailwind CLI binary cache directory

Available color families

slate, gray, zinc, neutral, stone, red, orange, amber, yellow, lime, green, emerald, teal, cyan, sky, blue, indigo, violet, purple, fuchsia, pink, rose

Special colors (black, white, transparent, current, inherit) are always included regardless of the StuColors filter.

Standalone CLI usage

Stu can also be run directly from the command line:

dotnet run --project src/Stu -- [options]

CLI options

Option	Default	Description
-o, --output <path>	tailwind-utilities.css	Output CSS file path
-c, --colors <families>	all	Comma-separated color families to include
--base-font-size <px>	16	Base font size for rem-to-px and line-height conversion
--minify	false	Output minified CSS
--cache-dir <path>	~/.cache/tailwind	Directory to cache the Tailwind binary
--force-download	false	Re-download the Tailwind CLI even if cached
-v, --verbose	false	Verbose logging

CLI examples

dotnet run --project src/Stu -- --colors gray,red,green -o utilities.css
dotnet run --project src/Stu -- --base-font-size 14 --minify -o utilities.min.css
dotnet run --project src/Stu -- --colors blue,indigo -o theme.css -v

What it does

Each run performs this pipeline:

1. Downloads the Tailwind v4 standalone CLI binary (cached locally)
2. Discovers all utility class names by fetching and parsing Tailwind's utilities.ts source from GitHub
3. Assembles candidate class names by combining discovered prefixes with value scales (spacing, colors, fractions, etc.)
4. Generates an input.css with @source inline() directives for all candidates
5. Runs the Tailwind CLI to produce a full CSS output
6. Parses the generated CSS and extracts all style rules
7. Resolves CSS custom properties (var(--spacing), var(--color-*), etc.) to their computed values, and evaluates calc() expressions
8. Filters out responsive prefixes, state variants, pseudo-classes, arbitrary value classes, and Tailwind internal --tw-* plumbing
9. Transforms rem/em to px, unitless line-height to px, and color functions (oklch, rgb, hsl) to hex
10. Aggregates, deduplicates, and sorts rules
11. Writes the final CSS file

Because utility names are discovered from Tailwind's source rather than hardcoded, Stu automatically picks up new utilities when Tailwind releases updates.

Features

• MSBuild integration — runs as a build action on publish, build, or both
• No Node.js — uses the Tailwind standalone CLI binary, downloaded automatically
• Auto-discovery — utility class names are parsed from Tailwind's source, not hardcoded
• All utility classes — layout, spacing, sizing, typography, backgrounds, borders, effects, filters, flexbox, grid, transforms, transitions, interactivity, SVG, accessibility, tables, and gradients
• Color family filtering — reduce output size by including only the color families you need
• Full variable resolution — all Tailwind CSS custom properties resolved to concrete values
• Unit conversion — all rem and em values converted to px, unitless line-height computed to px
• Color conversion — oklch(), oklab(), rgb(), hsl() all converted to #RRGGBB (or #RRGGBBAA for transparent colors)
• Clean output — no responsive breakpoints, no hover/focus/active variants, no arbitrary values, no internal --tw-* custom properties, no empty declarations
• Minified output option
• Cross-platform — works on Windows, Linux, and macOS (x64 and ARM64)

What's excluded (by design)

• Responsive prefixes (sm:, md:, lg:, etc.)
• State variants (hover:, focus:, active:, disabled:, etc.)
• Pseudo-elements (before:, after:, placeholder:, etc.)
• Arbitrary values (w-[100px], bg-[#ff0000], etc.)
• Stacking/combining classes
• @keyframes and @media blocks

Output format

The generated CSS contains one rule per utility class with fully computed values:

/* Generated by Stu — Tailwind Utility CSS Transformer | tailwindcss v4.2.2 */
/* 5200 rules | 2026-04-01 19:30:00 UTC */

.p-4 {
  padding: 16px;
}

.text-red-500 {
  color: #EF4444;
}

.text-lg {
  font-size: 18px;
  line-height: 28px;
}

.rounded-lg {
  border-radius: 8px;
}

.top-1\/2 {
  top: 50%;
}

Publishing the package

cd src/Stu
dotnet publish -c Release -o tools
dotnet pack -c Release --no-build

The resulting .nupkg in bin/Release/ contains the tool in tools/, MSBuild integration in build/ and buildTransitive/, and the README.

Project structure

src/
  Stu/
    build/              MSBuild .props and .targets for NuGet consumers
    buildTransitive/    Same, for transitive package references
    Config/             Color families, CLI options
    Discovery/          Auto-discovery of utility names from Tailwind source
    Download/           Tailwind CLI binary downloader + platform detection
    Generation/         input.css builder + Tailwind CLI runner
    Parsing/            Regex-based CSS parser
    Transformation/     Variable resolution, unit/color/line-height conversion,
                        filtering, aggregation
    Output/             CSS writer
    Program.cs          Pipeline orchestration
  Stu.Tests/
    Discovery/          Utility discovery + class name assembler tests
    Parsing/            CSS parser tests
    Transformation/     Unit converter, color converter, variable resolver,
                        line-height converter tests

Building from source

Requires .NET 10 SDK.

dotnet build src/Scott.Tailwind.UtilityClassDeposer.slnx
dotnet test src/Scott.Tailwind.UtilityClassDeposer.slnx