Create a dark mode theme switch with Gatsby and TailwindCSS

Published on January 13, 2021

Dark mode has been a recent feature in almost every technology. And in the release of Tailwind CSS v2.0, dark mode support was released as part of their feature.

While working with gatsby to create my portfolio, I couldn’t find an easy guide. But after so much research, I was able to come up with this solution. And I believe this solution will also help you to easily get things to build up.

Setting up the project

If this is your first time working with gatsby, you should run npm install -g gatsby-cli on your terminal to create a global installation on your computer. But I’ll also recommend that you visit gatsby’s quick guide.

Step 1: create a new gatsby project from the default starter

gatsby new dark-mode && cd dark-mode

Your folder structure should look like this:

- src  
  - components  
    - header.js  
    - image.js  
    - layout.css  
    - layout.js  
    - seo.js  
  - images  
    - gatsby-astronaut.png  
    - gatsby-icon.png  
  - pages  
    - 404.js  
    - index.js  
    - page-2.js  
    - using-typescript.tsx  
- .gitignore  
- .prettierignore  
- .prettierrc  
- gatsby-browser.js  
- gatsby-config.js  
- gatsby-node.js  
- gatsby-ssr.js  
- LICENSE  
- package-lock.json  
- package.json  
- README.md

Step 2: Let’s install and configure tailwindcss in our project.

To install:

npm run tailwindcss

Run the below command to generate tailwind.config.js file

npx tailwindcss init

Step 3: Install and setup gatsby-plugin-postcss. This is a tool for transforming CSS with JavaScript.

Run the below command to Install:

npm install postcss gatsby-plugin-postcss

To setup:

Include the plugin in your gatsby-config.js file.

module.exports = {  
    ...  
    plugins: [  
      `gatsby-plugin-postcss`,  
       ...

Create a postcss.config.js file in your root directory and add the below in it.

module.exports = () => ({ plugins: [require("tailwindcss")],})

Step 4: Let’s create our CSS file in a static folder

Create a static folder in the root directory. In it, create a styles folder that contains our CSS file; let’s say index.css

- src  
- static  
    - styles  
       - index.css

Include the below tailwind directives in your index.css file.

@tailwind base;

@tailwind components;

@tailwind utilities;

Step 5: Let’s build out tailwind CSS

Include the below script in our package.json file. This script will help to generate a fully compiled tailwind.css file in the styles folder

"scripts": {  
    ... 
    "build:tailwind": "tailwind build static/styles/index.css -o  static/styles/tailwind.css",

Now, run the below command

npm run build:tailwind

Finally, Include the build CSS file path in gatsby-browser.js file

// Import tailwind styles

import "./static/styles/tailwind.css"

Yaay!, we’ve successfully configured our tailwind CSS with gatsby 🍿.

Next, let us make some changes, then we run our server

Update layout.js file to the below code.

import React from "react"  
import PropTypes from "prop-types"  
import { useStaticQuery, graphql } from "gatsby"
import Header from "./header"  
import "./layout.css"

const Layout = ({children }) => {  
   const data = useStaticQuery(graphql`  
                  query SiteTitleQuery {  
                        site {  
                           siteMetadata {  
                               title  
                            }  
                         }  
                    }  
                `)
return (  
    <div className="bg-gray-600 text-white"> 
        <Header   
          siteTitle={data.site.siteMetadata?.title || `Title`}  
        /> 
        <main className="p-10">  
           {children}  
        </main> 
      <footer style={{ marginTop: `2rem` }}>  
             © {new Date().getFullYear()}, Built with{` `}  
             <a href="https://www.gatsbyjs.com">Gatsby</a>  
      </footer> 
   </div>  
  )  
}

Layout.propTypes = {  
   children: PropTypes.node.isRequired,  
}

export default Layout

Run npm start on your terminal to start the development server
You can now view the project on the browser with http://localhost:8000/

Your project should look like this:

Build dark-mode theme

Up till now, we’re yet to talk about our generated tailwind.config.js. Currently, you should have something like this:

module.exports = {  
    purge: [],  
    darkMode: false, // or 'media' or 'class'  
    theme: {  
        extend: {},  
    },  
    variants: {  
        extend: {},  
    },  
    plugins: [],  
}

Now, to enable darkmode on tailwind, set the darkMode option in your tailwind.config.js file to class. This will enable us to toggle the theme when dark mode is enabled.

Next, let us enable dark mode on our project

Step 1: Update the return statement in layout.js to this:

<div className="bg-gray-600 dark:bg-gray-900 text-white">
   <Header siteTitle={data.site.siteMetadata?.title || `Title`} /> 
    <main className="p-10 ">{ children }</main> 
    <footer style={{ marginTop: `2rem`,}}>  
       © {new Date().getFullYear()}, Built with{` `}  
      <a href="https://www.gatsbyjs.com">Gatsby</a>  
    </footer>
</div>

Step 2: There are two things to do here:

Stop the running server with ctrl + c
Rebuild the tailwind.css file again. This will generate an updated file that includes classes like .dark:bg-gray-900

npm run build:tailwind

Step 3: Install and setup gatsby-plugin-dark-mode. This plugin help to handle some of the details of implementing a dark mode theme.

To install:

npm install gatsby-plugin-dark-mode

To setup:

Include the plugin in your gatsby-config.js file.

module.exports = {  
    ...  
    plugins: [  
        `gatsby-plugin-postcss`,  
         `gatsby-plugin-dark-mode`  
          ...

Create a themeToggle.js file in your component folder and include the following in it:

import React from "react"  
import { ThemeToggler } from "gatsby-plugin-dark-mode"

export default function ThemeToggle() {  
     return (  
       <ThemeToggler>  
        {({ theme, toggleTheme }) => ( 
        <label> <input type="checkbox"   
               onChange={e =>   
                 toggleTheme(e.target.checked ? 'dark' : 'light')}  
                  checked={theme === 'dark'}  
               />{' '}    
             
            Dark mode             
          </label>      
           
         )}  
        </ThemeToggler>  
     )  
}

At this stage, the dark mode theme (via the prefers-color-scheme CSS media query) is automatically set.

Step 3: Import the themeToggle.js file in layout.js

import React from "react"  
import PropTypes from "prop-types"  
import { useStaticQuery, graphql } from "gatsby"
import Header from "./header"  

import ThemeToggle from "./themeToggle" 
import "./layout.css"

const Layout = ({ children }) => {  
   const data = useStaticQuery(graphql`  
                  query SiteTitleQuery {  
                        site {  
                           siteMetadata {  
                               title  
                            }  
                         }  
                    }  
                `)
return (  
    <div className="bg-gray-600 dark:bg-gray-900 text-white">
       <Header   
          siteTitle={data.site.siteMetadata?.title || `Title`}  
        /> 
      <ThemeToggle /> 
      <main className="p-10">  
           {children}  
      </main> 
      <footer style={{ marginTop: `2rem` }}>  
             © {new Date().getFullYear()}, Built with{` `}  
             <a href="https://www.gatsbyjs.com">Gatsby</a>  
      </footer> 
   </div>  
  )  
}

Layout.propTypes = {  
   children: PropTypes.node.isRequired,  
}

export default Layout

If you’re currently at this stage, congratulation to you. We’ve successfully built a dark mode theme switch using gatsby and tailwind.

Now, Let’s test our project by running our development server again

npm run start

Yeeeaah! ☺️, your project should look like this: ( please, don’t mind the file compression. )

Final demo

Since this tutorial only focused on the functionality and not the styling, you can always be creative by making things look better.

I’ve provided links below, if you want to know more about the resources we used:

Gatsby plugin dark mode: https://www.gatsbyjs.com/plugins/gatsby-plugin-dark-mode/
Tailwind dark mode: https://tailwindcss.com/docs/dark-mode

You can like and do leave a comment for any contribution to this article on medium. Thank you.