RunCSS

RunCSS is the runtime equivalent of TailwindCSS, featuring the same CSS utility class names, but with no build step required. It achieves this by generating CSS on the fly with JavaScript.

RunCSS comes with batteries included. By default all additional variants such as hover, active, visited, group-hover, sm, lg etc work with all class names. All packaged in a single 25kb (8kb after compression) JS file!

Usage

Add to <head>:

  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/runcss/dist/runcss.min.css">
  <script src="https://cdn.jsdelivr.net/npm/runcss/dist/runcss.min.js" defer watch></script>

Done! RunCSS will parse the documents and generate the corresponding classes, with no further configuration required. RunCSS will also watch for new element insertions and parse them. Remove the watch attribute to disable this feature.

Check the examples/ directory for some examples.

Avoid element popup

You may add the runcss-cloak attribute to any element to hide it until RunCSS processes it.

For example:

<body runcss-cloak>
  <img class="w-3 h-3" src="mylargeimage.png">
</body>

Custom configuration

TODO - WORK IN PROGRESS Before loading runcss.js, add the following script:

<script>
window.runcssConfig = {
  colors: {
    'main': '#fff',
    'secondary': {
      100:  '#09132aa'
    },
  },
  screens: {
    sm: '480px',
    md: '768px',
    lg: '976px',
    xl: '1440px',
  },
  fontFamily: {
    sans: ['Graphik', 'sans-serif'],
    serif: ['Merriweather', 'serif'],
  },
}
</script>
<script></script>

You may use it to either extend or override default values. Currently, this is not yet implemented. colors, screens and fontFamily.

Advanced usage as module

<script type="module">
  import RunCSS, {extendRunCSS} from "https://cdn.jsdelivr.net/npm/runcss/dist/runcss.min.mjs"

  // Add things to the RunCSS templates
  extendRunCSS( ({defaultsTemplate, ruleTemplate, shortcuts, states}) => {
    states.modifiers['myclass'] = '.myclass'
    return {defaultsTemplate, ruleTemplate, shortcuts, states}
  })

  // Setup theme
  const { processClasses, startWatching, stopWatching, exportCSS } = RunCSS({
    colors: {
      'main': '#fff',
    },
    //.... same options as above
  })

  // Add classes
  processClasses('sm:text-red text-blue') // don't worry about duplicates

  // Iterate through document
  for(const element of document.querySelectorAll('*[class]')) {
    processClasses(element.getAttribute("class"))
  }

  // Start watching for changes
  startWatching(document.getElementById('hello')) // if not specified, fallback to document.body

  // Stop watching
  stopWatching()

  // Log generated CSS file
  console.log(exportCSS())

  // Remove runcss-cloak attribute
  const hiddenNodes = document.querySelectorAll('*[runcss-cloak]')
  for(let node of hiddenNodes){
    node.removeAttribute('runcss-cloak')
  }
</script>

Caveats and differences with TailwindCSS

Currently, this project is still under development, but it aims to cover the totality of TailwindCSS classes.

If you find something missing, feel free to open an issue.

By design, this parser is way less strict than Tailwind's one. This allows smaller builds and faster load times, but also means that wrong values may be turned into CSS rules regardless. This is intentional, because the browser will discard those rules anyway.

VSCode Intellisense

To enable Tailwind's autocompletion, install the official Tailwind extension, and create an empty file called tailwind.config.js in the same folder of your html files.

Build / contribute

Clone this repository and use bun to install dependencies:

git clone https://github.com/lucafabbian/runcss.git
cd runcss
bun i

Then, you may use:

bun run build    # Build for production
bun run dev      # Build, watch for changes + start server with live reload!

Authors and License

Current author: Luca Fabbian luca.fabbian.1999@gmail.com

Based on RunCSS of mudgen, follow him on twitter.

Distributed under MIT License.

mudgen / runcss