How to apply arbitrary styles with tailwind JIT

Tailwind is a utility first CSS framework that gives developers full control over styling web components. Unlike component frameworks or libraries, Tailwind doesn’t restrict you to preexisting components that are tweakable via props and options. With Tailwind, you build from the ground up, using utility classes in their smallest form.

Sheesh! But I’d rather have someone else do the job. I like component libraries better. Well, there’s Headless UI — completely unstyled UI components that integrate well with Tailwind CSS (their words, not mine).

In March, Adam Wathan (Creator of Tailwind) announced the biggest updates to Tailwind CSS - The Tailwind JIT.

One major highlight about this update is that you now get to write less custom CSS. Let’s understand how that works.

With Tailwind, we would usually start out by setting up our themes and variants within the tailwind.config.js file. Something like this:

module.exports = {
  theme: {
    colors: {
      gray: '#CFD8DC',
      blue: '#2196F3',
      red: '#EF5350',
      pink: '#F48FB1',
    },
    fontFamily: {
      sans: ['Graphik', 'sans-serif'],
      serif: ['Merriweather', 'serif'],
    },
    extend: {
      spacing: {
        '128': '32rem',
        '144': '36rem',
      },
      borderRadius: {
        '4xl': '2rem',
      }
    }
  },
  variants: {
    extend: {
      borderColor: ['focus-visible'],
      opacity: ['disabled'],
    }
  }
}

The theme section is where we customize anything related to the visual design/design system of our site. Here, we can specify our color palette, font family, border-radius sizes, and the like. Without customization, Tailwind comes with specific values for all of these style properties, like colors for example.

Looking at this chart, we know that we can customize 10 shades of the color “Red”. The problem, however, comes in when we need, say, one or two additional shades (insatiable humans, eh?). Of course, Tailwind’s configuration file can help us achieve this:

// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      colors: {
        red: {
          350: '#E53935'
        },
      }
    }
  }
}

We shouldn’t have to do this if we only need these shades in one or two parts of our application, and they aren’t necessary for theming. This is where Arbitrary Styles with Tailwind JIT compiler come in. With Arbitrary Styles, you can specify the hyper-specific style you need on elements without needing to update it in your config file…Yes, Sam, you can now get rid of those inline style attributes 👀.

Let’s put this to a test. I’ll spin up a Vue project and install Tailwind, and after that, we’ll set up JIT mode. Note that you can do this with whatever Javascript frontend framework you work with. Tailwind is framework agnostic.

Psst! Here’s a Vue and no-framework setup for Tailwind:

vue create tailwind-ab-styles

Navigate into the project directory:

cd tailwind-ab-styles

Install and Set up Tailwind CSS. Here’s a quick guide to set up Tailwind CSS in your Vue project:

https://www.educative.io/answers/how-to-setup-tailwind-css-in-vue-3

After setting up Tailwind, you can enable JIT by updating your tailwind.config.js and changing the “mode” property to “JIT”:

module.exports = {
  mode: 'jit',  // update this line
  purge: ['./index.html', './src/**/*.{vue,js,ts,jsx,tsx}'],
  darkMode: false, // or 'media' or 'class'
  ...
};

Let’s spin up the Vue server and see what this looks like:

yarn serve

You might get a similar warning from the bundler about the JIT engine currently in preview when you start the server:

Using Arbitrary Styles

I’ve updated the App.vue file to a simple markup with basic Tailwind classes:

<template>
  <div class="justify-center flex bg-yellow-300 items-center h-screen">
    <div class="text-4xl">
      Hello 👋🏼
    </div>
  </div>
</template>

<script>
export default {
  name: 'App',
};
</script>

Result:

In the markup above, we have a text “Hello” with a div of class “text-4l” wrapped around it. Tailwind provides 10 “font-size” utility classes that we can use, and their values range from 0.75rem to 8rem. Say we just wanted this text to be size 9rem. With arbitrary styles, we don’t have to configure another utility class for this case; instead, we can do this:

<div class="text-[9rem]">
  Hello 👋🏼
</div>

And there you have it, a huge text of size 9rem. This saves us the pain of littering our markup with inline styles.

Let’s add in a box below the “hello” text and set its width, height, and background color using Arbitrary values:

<div class="w-[300px] h-[200px] bg-[#FFECB3] rounded-[20px] ml-[40px]"></div>

We can also use this for screen variants as well:

<div class="w-[300px] h-[200px] md:bg-[#FFECB3] rounded-[20px] ml-[40px] lg:ml-[-400px] lg:mb-[430px]"></div>

This also works for grids and layouts. Check out the documentation for advanced applications.

Limitation

You can only @apply classes that are part of coregenerated by plugins, or defined within a @layer rule. You can’t @apply arbitrary CSS classes that aren’t defined within a @layer rule. — docs

@apply is a directive used to inline an existing utility class into your custom CSS. Currently, this is the only known limitation with arbitrary values. Have fun tinkering with it!

Cheers ☕️