ruby - Compass css_parser ERROR: Failed to build gem native extension -

ruby - Compass css_parser ERROR: Failed to build gem native extension -

i've began installing sass , compass. next step install css_parser. pretty easy step but... inserted told website. insert terminal:

sudo gem install css_parser

after seconds begins install alert , i'm stuck:

sudo gem install compass installed compass-0.12.2 1 gem installed installing ri documentation compass-0.12.2... installing rdoc documentation compass-0.12.2... daniels-macbook-pro:~ danielramirez$ sudo gem install css_parser building native extensions. take while... error: error installing css_parser: error: failed build gem native extension. /system/library/frameworks/ruby.framework/versions/1.8/usr/bin/ruby extconf.rb mkmf.rb can't find header files ruby @ /system/library/frameworks/ruby.framework/versions/1.8/usr/lib/ruby/ruby.h gem files remain installed in /library/ruby/gems/1.8/gems/json-1.7.7 inspection. results logged /library/ruby/gems/1.8/gems/json-1.7.7/ext/json/ext/generator/gem_make.out

what mean , how follow?

ruby terminal gem