Extend · Bootstrap 2.2.0 Documentation

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.

Why LESS?

One of Bootstrap's creators wrote a quick blog post about this, summarized here:

Bootstrap compiles faster ~6x faster with Less compared to Sass
Less is written in JavaScript, making it easier to us to dive in and patch compared to Ruby with Sass.
Less is more; we want to feel like we're writing CSS and making Bootstrap approachable to all.

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

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

Since our CSS is written with Less and utilizes variables and mixins, it needs to be compiled for final production implementation. Here's how.

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

Quickly start any web project by dropping in the compiled or minified CSS and JS. Layer on custom styles separately for easy upgrades and maintenance moving forward.

Setup file structure

Download the latest compiled Bootstrap and place into your project. For example, you might have something like this:

   app/
       layouts/
       templates/
   public/
       css/
           bootstrap.min.css
       js/
           bootstrap.min.js
       img/
           glyphicons-halflings.png
           glyphicons-halflings-white.png

Utilize starter template

Copy the following base HTML to get started.

<html>
  <head>
    <title>Bootstrap 101 Template</title>
    <!-- Bootstrap -->
    <link href="public/css/bootstrap.min.css" rel="stylesheet">
  </head>
  <body>
    <h1>Hello, world!</h1>
    <!-- Bootstrap -->
    <script src="public/js/bootstrap.min.js"></script>
  </body>
</html>

Layer on custom code

Work in your custom CSS, JS, and more as necessary to make Bootstrap your own with your own separate CSS and JS files.

<html>
  <head>
    <title>Bootstrap 101 Template</title>
    <!-- Bootstrap -->
    <link href="public/css/bootstrap.min.css" rel="stylesheet">
    <!-- Project -->
    <link href="public/css/application.css" rel="stylesheet">
  </head>
  <body>
    <h1>Hello, world!</h1>
    <!-- Bootstrap -->
    <script src="public/js/bootstrap.min.js"></script>
    <!-- Project -->
    <script src="public/js/application.js"></script>
  </body>
</html>

Extending Bootstrap

Built with LESS