Installation

Get started with Nightfall CSS in under a minute.

Quick Start

Install Nightfall CSS as a dev dependency:

npm install nightfall-css --save-dev

Or use it directly with npx:

npx nightfall-css scan --url http://localhost:3000

Requirements

  • Node.js 18 or later
  • A running development server (the URL Nightfall will scan)
  • Playwright (installed automatically on first run)

Initialize Config

Create a nightfall.config.json file:

npx nightfall-css init

This creates a config file with sensible defaults. You can customize the URL, routes, output format, preset, and more.

First Scan

Start your dev server, then run:

# Start your app
npm run dev

# In another terminal, scan it
npx nightfall-css run

Nightfall will auto-detect whether your app is light or dark, analyze every color relationship, and generate the opposite theme.