Bootstrap

Extending Bootstrap

Extend Bootstrap with LESS, a CSS preprocessor, to take advantage of the variables, mixins, and more used to build Bootstrap's CSS.

Built with LESS

Why LESS?

Bootstrap is made with LESS at its core, a dynamic stylesheet language created by our good friend, Alexis Sellier. It makes developing systems-based CSS faster, easier, and more fun.

What's included?

As an extension of CSS, LESS includes variables, mixins for reusable snippets of code, operations for simple math, nesting, and even color functions.

Learn more

LESS CSS

Visit the official website at http://lesscss.org to learn more.

Variables

Managing colors and pixel values in CSS can be a bit of a pain, usually full of copy and paste. Not with LESS though—assign colors or pixel values as variables and change them once.

Mixins

Those three border-radius declarations you need to make in regular ol' CSS? Now they're down to one line with the help of mixins, snippets of code you can reuse anywhere.

Operations

Make your grid, leading, and more super flexible by doing the math on the fly with operations. Multiply, divide, add, and subtract your way to CSS sanity.

Compiling Bootstrap with LESS

Note: If you're submitting a pull request to GitHub with modified CSS, you must recompile the CSS via any of these methods.

Tools for compiling

Node with makefile

Install the LESS command line compiler, JSHint, Recess, and uglify-js globally with npm by running the following command:

$ npm install -g less jshint recess uglify-js

Once installed just run make from the root of your bootstrap directory and you're all set.

Additionally, if you have watchr installed, you may run make watch to have bootstrap automatically rebuilt every time you edit a file in the bootstrap lib (this isn't required, just a convenience method).

Command line

Install the LESS command line tool via Node and run the following command:

$ lessc ./less/bootstrap.less > bootstrap.css

Be sure to include --compress in that command if you're trying to save some bytes!

Javascript

Download the latest Less.js and include the path to it (and Bootstrap) in the <head>.

<link rel="stylesheet/less" href="/path/to/bootstrap.less">
<script src="/path/to/less.js"></script>

To recompile the .less files, just save them and reload your page. Less.js compiles them and stores them in local storage.

Unofficial Mac app

The unofficial Mac app watches directories of .less files and compiles the code to local files after every save of a watched .less file.

If you like, you can toggle preferences in the app for automatic minifying and which directory the compiled files end up in.

More Mac apps

Crunch

Crunch is a great looking LESS editor and compiler built on Adobe Air.

CodeKit

Created by the same guy as the unofficial Mac app, CodeKit is a Mac app that compiles LESS, SASS, Stylus, and CoffeeScript.

Simpless

Mac, Linux, and PC app for drag and drop compiling of LESS files. Plus, the source code is on GitHub.