Tailwind CSS for Rails
Tailwind CSS is a utility-first CSS framework packed with classes like flex, pt-4, text-center and rotate-90 that can be composed to build any design, directly in your markup.
This gem wraps the standalone executable version of the Tailwind CSS 3 framework. These executables are platform specific, so there are actually separate underlying gems per platform, but the correct gem will automatically be picked for your platform. Supported platforms are Linux x64, macOS arm64, macOS x64, and Windows x64. (Note that due to this setup, you must install the actual gems – you can't pin your gem to the github repo.)
You can customize the Tailwind build through the
config/tailwind.config.js file, just like you would if Tailwind was running in a traditional node installation. All the first-party plugins are supported.
The installer will create your Tailwind input file in
app/assets/stylesheets/application.tailwind.css. This is where you import the plugins you want to use, and where you can setup your custom
@apply rules. When you run
rails tailwindcss:build, this input file will be used to generate the output in
app/assets/builds/tailwind.css. That's the output CSS that you'll include in your app (the installer automatically configures this, alongside the Inter font as well).
If you need to use a custom input or output file, you can run
bundle exec tailwindcss to access the platform-specific executable, and give it your own build options.
When you're developing your application, you want to run Tailwind in watch mode, so changes are automatically reflected in the generated CSS output. You can do this either by running
rails tailwindcss:watch as a separate process, or by running
./bin/dev which uses foreman to starts both the Tailwind watch process and the rails server in development mode.
With Rails 7 you can generate a new application preconfigured with Tailwind by using
--css tailwind. If you're adding Tailwind later, you need to:
./bin/bundle add tailwindcss-rails
Building in production
tailwindcss:build is automatically attached to
assets:precompile, so before the asset pipeline digests the files, the Tailwind output will be generated.
Conflict with sassc-rails
Tailwind uses modern CSS features that are not recognized by the
sassc-rails extension that was included by default in the Gemfile for Rails 6. In order to avoid any errors like
SassC::SyntaxError, you must remove that gem from your Gemfile.