Revision as of 04:02, 12 April 2013 by Martin Dougiamas (talk | contribs) (Using Recess)

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LESS extends CSS with dynamic behavior such as variables, mixins, operations and functions. It's an advanced way of writing CSS that we use in some themes within Moodle.

Browsers don't interpret it themselves, however, so LESS files need to be converted into normal CSS before use.

Recess is one tool used to compile and compress LESS into CSS under *nix based systems. There are many others tools for LESS.

The bootstrap theme

Moodle's bootstrap base theme has rules written using LESS.

The main LESS file is theme/bootstrap/less/moodle.less, with additional files in theme/bootstrap/less/moodle/ imported by the main file.

After compiling the LESS files, CSS ends up in theme/bootstrap/style/generated.css. This file should not be edited manually.



Installing Recess under Ubuntu

The following commands should be run to install Recess

sudo apt-get install npm node
npm install recess -g

Installing Recess on Mac OS X

1. Install the basic node packages from the web site: http://nodejs.org (or use your favourite package manager).

2. On the command line, install recess like this:

    npm install recess -g

Using Recess

After editing the LESS files, compile your CSS as follows:

cd theme/boostrap/less/
recess --compile --compress moodle.less > ../style/generated.css

This will compile and compress the moodle.less file (and all the LESS and CSS files it imports) into a single file, generated.css, and store it in the style folder of the bootstrap theme.

NOTE: if you are getting empty generated.css files, this is being caused by a parsing error in your LESS code. You will need to examine what you have altered or written to make sure it is complete and the syntax is correct.


Download WinLess and install it.

Using WinLess