Installing Bullet Train Themes on Other Rails Projects

Bullet Train themes can be installed on Vanilla Rails projects.

Our main theme, called Light, uses erb partials to give you native Rails views with Hotwire-powered components. It's built on tailwindcss, uses postcss to allow for local CSS overrides and uses esbuild for fast javascript compilation and to support javascript-side CSS imports.

In addition to providing a nice set of UI components, you'll get access to nice_partials, Bullet Train's own lightweight answer for creating erb partials with ad-hoc named content areas, which we think is just the right amount of magic for making erb-based components.

Note: we have special instructions for installing themes on Jumpstart Pro projects.


  1. Installation Instructions
  2. Optional Configurations for switching colors, theme gems
  3. Using Locales for fields on new models
  4. Partials that require special instructions, exclusions
  5. Modifying ejected partials

1. Installation Instructions

Ensure your Rails Project uses esbuild and tailwindcss with postcss

You'll need to make sure your Rails project is set up to use esbuild, tailwindcss and postcss.

The easiest way to see what your project should include is to create a separate project, for reference, generated via this command:

rails new rails-new-esbuild-tailwind-postcss --css tailwind --javascript esbuild

Add the theme gem

These instructions assume you're installing the Light theme bundled with Bullet Train.

bundle add bullet_train-themes-light

Or add the following to your Gemfile:

gem "bullet_train-themes-light"

And then run:

bundle install

Add npm packages

The Light theme requires the following npm packages to be installed

yarn add @bullet-train/bullet-train @bullet-train/fields autoprefixer @rails/actiontext postcss-extend-rule postcss-import

Update your app/javascript/controllers/index.js with the following lines:

import { controllerDefinitions as bulletTrainControllers } from "@bullet-train/bullet-train"
import { controllerDefinitions as bulletTrainFieldControllers } from "@bullet-train/fields"


Overwrite tailwind and esbuild config files, add bin stubs from Bullet Train

curl -L "" -o esbuild.config.js
curl -L "" -o postcss.config.js
curl -L "" -o tailwind.config.js
curl -L "" -o bin/theme
curl -L "" -o bin/link
chmod +x bin/theme bin/link

Update build:css in package.json

In package.json, replace the build and build:css entries under scripts with:

"build": "THEME=\"light\" node esbuild.config.js",
"build:css": "bin/link; THEME=\"light\" tailwindcss --postcss --minify -c ./tailwind.config.js -i ./app/assets/stylesheets/application.tailwind.css -o ./app/assets/builds/application.tailwind.css"

Update esbuild.config.js

Remove or comment out the following line from esbuild.config.js:

"intl-tel-input-utils": path.join(process.cwd(), "app/javascript/intl-tel-input-utils.js"),

Define current_theme helper

In your app/helpers/application_helper.rb, define:

def current_theme

Add stylesheet_link_tag to <head>

Make sure you have the following three lines in your <head>, which should be defined in app/views/layouts/application.html.erb:

<%= stylesheet_link_tag "application", media: "all", "data-turbo-track": "reload" %>
<%= stylesheet_link_tag "application.tailwind", media: "all", "data-turbo-track": "reload" %>
<%= javascript_include_tag 'application.light', 'data-turbo-track': 'reload' %>

Import the Theme Style Sheet

To your application.tailwind.css file, add the following line:

@import "$ThemeStylesheetsDir/application.css";

Also be sure to replace the following lines:

@tailwind base;
@tailwind components;
@tailwind utilities;

To the following lines:

@import "tailwindcss/base";
@import "tailwindcss/components";
@import "tailwindcss/utilities";

Unless this is done, postcss-import doesn't work correctly.

Add Themify Icons, jQuery (for now) and trix editor support

Note: jQuery is needed for some of our components, but defining window.$ won't be required soon. See PR

yarn add @icon/themify-icons jquery

To your application.js, add the following line:

import jquery from "jquery"
window.jQuery = jquery
window.$ = jquery


import { trixEditor } from "@bullet-train/fields"

Add Locale Strings

Add these to your config/locales/en.yml under en:

      date_field: "%m/%d/%Y"
      date_and_time_field: "%m/%d/%Y %l:%M %p"
      date_controller: "MM/DD/YYYY"
    am: AM
    pm: PM
      date_field: "%m/%d/%Y"
      date_and_time_field: "%m/%d/%Y %l:%M %p"
      date_controller: "MM/DD/YYYY h:mm A"
    firstDay: 1
    separator: " - "
    applyLabel: "Apply"
    cancelLabel: "Cancel"
    fromLabel: "From"
    toLabel: "To"
    customRangeLabel: "Custom"
    weekLabel: "W"
    - "Su"
    - "Mo"
    - "Tu"
    - "We"
    - "Th"
    - "Fr"
    - "Sa"
    - "January"
    - "February"
    - "March"
    - "April"
    - "May"
    - "June"
    - "July"
    - "August"
    - "September"
    - "October"
    - "November"
    - "December"
    today: Today
    yesterday: yesterday
    last7Days: Last 7 Days
    last30Days: Last 30 Days
    thisMonth: This Month
    lastMonth: Last Month
      other: Other
      cancel: Cancel
      all: All

2. Optional Configurations for switching colors, theme gems

For Setting the Active Color

curl -L "" -o initializers/theme.rb

Add the following classes to your html tag for your layout:

<html class="theme-<%= BulletTrain::Themes::Light.color %> <%= "theme-secondary-#{BulletTrain::Themes::Light.secondary_color}" if BulletTrain::Themes::Light.secondary_color %>"

For Switching Between Installed Themes

If you'd like to create your own theme but would still like to build on top of :light, you'll need to have both gems installed and you'll be able to switch the current theme this way.

Change the current_theme value in app/helpers/application_helper.rb

def current_theme

To change to use a different theme:

  1. Change the value returned by current_theme to the new theme name
  2. Change the name of the THEME env var defined in build and build:css in package.json
  3. Change the name of the theme in the javascript_include_tag in the <head>.

3. Using Locales for fields on new models

The theme's field partials work best with locale strings that are defined for the model you're creating.

Example: you've created a Project model. Here we'll create a projects.en.yml

  1. Run curl -L "" -o config/locales/projects.en.yml
  2. Search and replace projects.en.yml for scaffolding/completely_concrete/tangible_things, Tangible Things, Tangible Thing, tangible_things and tangible_thing. Replace with projects, Projects, Project, projects and project respectively.
  3. Remove strings you won't be using. In particular, look for comments with "skip" or "scaffolding".

Some fields use locale strings to drive their options. In the tangible_things.en.yml template file, look for super_select_value, multiple_option_values and others.

You'll notice & and * symbols prefixing some special keys in the yml file. Those are anchors and aliases and they help you reduce repetition in your locale strings.

To learn more about how these locales are generated in Bullet Train, see the documentation on Bullet Train's Super Scaffolding

4. Partials that require special instructions, exclusions

For using boolean-type fields (options, buttons)

In ApplicationController, add this:

include Fields::ControllerSupport

For the file_field partial

# in the model
has_one_attached :file_field_value
after_validation :remove_file_field_value, if: :file_field_value_removal?
attr_accessor :file_field_value_removal
def file_field_value_removal?
def remove_file_field_value
# in the controller's strong_params

For image, active_storage_image

See account/users_helper in BT core repo for implementing photo_url_for_active_storage_attachment

5. Modifying ejected partials

For ejecting a theme partial and modifying it

We recommend firing up a Bullet Train project and using its bin/resolve (see docs on Indirection) to get a copy of the partial field locally to modify.