Tailwind CSS for Rails#

Build consistent, dark-mode-ready component patterns in Rails ERB views using Tailwind utilities and reusable partials.

Quick Start#

Add a class name helper to collapse conditional logic:

ruby

# app/helpers/application_helper.rb
def cn(*classes)
  classes.flatten.compact.join(' ').split.uniq.join(' ')
end

Use it in views to combine base and conditional classes:

erb

<div class="<%= cn('px-4', active ? 'bg-blue-500' : 'bg-gray-200') %>">
  Content
</div>

Standard full-width container with responsive padding:

erb

<div class="mx-auto max-w-7xl px-4 py-8 sm:px-6 lg:px-8">
  <!-- Page content -->
</div>

Badge Pattern#

erb

<span class="inline-flex items-center rounded-full bg-green-100 px-3 py-1 text-sm font-medium text-green-800 dark:bg-green-900 dark:text-green-100">
  Label
</span>

Colors: Yellow=warning, Blue=info, Green=success, Red=danger, Gray=neutral

Light: bg-{color}-100 + text-{color}-800 | Dark: dark:bg-{color}-900 + dark:text-{color}-100

Common Components#

Card with border and shadow:

erb

<div class="rounded-lg border border-gray-200 bg-white shadow-sm dark:border-gray-800 dark:bg-gray-950">
  <div class="px-6 py-4">
    <!-- content -->
  </div>
</div>

Table wrapper with responsive shadow:

erb

<div class="overflow-hidden shadow ring-1 ring-black ring-opacity-5 md:rounded-lg">
  <table class="w-full divide-y divide-gray-200">
    <thead>...</thead>
    <tbody>...</tbody>
  </table>
</div>

Tab navigation with underline:

erb

<nav class="flex space-x-8 border-b border-gray-300">
  <% tabs.each do |tab| %>
    <% active = current_tab == tab %>
    <%= link_to tab_path(tab),
        class: "py-2 px-1 border-b-2 font-medium text-sm #{active ? 'border-blue-500 text-blue-600' : 'border-transparent text-gray-600 hover:text-gray-700'}" do %>
      <%= tab.humanize %>
    <% end %>
  <% end %>
</nav>

Best Practices#

1. Use the cn() helper for all conditional class logic — it deduplicates and removes blanks.
2. Pair light and dark classes always — bg-white dark:bg-gray-950, text-gray-900 dark:text-gray-100.
3. Mobile-first responsive design — use sm:, md:, lg: prefixes for breakpoints.
4. Extract repeated patterns into partials — _badge.html.erb, _button.html.erb, _card.html.erb.
5. Use semantic color names — yellow for warnings, green for success, red for errors.
6. Ensure sufficient contrast in both light and dark modes.
7. Test accessibility with screen readers and keyboard navigation.

References#

• references/components.md — Reusable badge, button, and card partials with usage examples.
• references/dark-mode-responsive.md — Dark mode setup, responsive patterns, and animation utilities.