It will help you to develop with fun.
Update Ruby
Open the black screen.(Terminal)
sudo su
enter your password...and execute the following lines to upgrade your system
gem update --system exit
Install Sass
SASS/SCSS is a meta language.
http://sass-lang.com/
sudo gem install sass
update : $ sudo gem update sass
Install Compass
Compass compiles SASS/SCSS files and offers a CSS3 framework.
http://compass-style.org/
sudo gem install compass
update : $ sudo gem update compass
Setup a new project
open the desired project
cd <to your folder project>
compass init
...
Structure
project
|_index.php
|_sass
|_style.scss
|_partials
|_partial.scss
|_modules
|_css
|_style.css
|_config.rb
Config.rb
Example :
# Require any additional compass plugins here. # Set this to the root of your project when deployed: http_path = "../" css_dir = "../css" sass_dir = "sass" images_dir = "images" javascripts_dir = "javascripts" # You can select your preferred output style here (can be overridden via the command line): # output_style = :expanded or :nested or :compact or :compressed # To enable relative paths to assets via compass helper functions. Uncomment: # relative_assets = true # To disable debugging comments that display the original location of your selectors. Uncomment: # line_comments = false # If you prefer the indented syntax, you might want to regenerate this # project again passing --syntax sass, or you can uncomment this: # preferred_syntax = :sass # and then run: # sass-convert -R --from scss --to sass sass scss && rm -rf sass && mv scss sass
Setup an existing project
Update Ruby/Compass/Sass. Then go to the existing project dir
cd <to an existing folder project>
Make sure that a config.rb file exists.
Launch
compass watch
and pray 
Generate CSS
To detect changes in your SASS/SCSS files and generate automatically CSS files. Execute into the terminal :
compass watch
Terminal displays:
>>> Compass is polling for changes. Press Ctrl-C to Stop.
Press Ctrl-C to leave...
You can although launch the compilation manually when needed.
compass compile