ruby css sass scss mixin slim
http://qiita.com/one-a/items/2758511326c09200fded
http://css-happylife.com/archives/2012/0127_0020.php
http://www7b.biglobe.ne.jp/~makandat/gg_sites/Sinatra_Diary_01.html
http://www7b.biglobe.ne.jp/~makandat/gg_sites/Sinatra_Diary_01.html
http://qiita.com/hiroki_y/items/06f5780543bec988d8b7
http://qiita.com/udzura/items/2ff60b386a6a0bcb3b4e
http://inmonochrome.blogspot.hk/2012/05/sinatra-5-css.html
http://cu39.hateblo.jp/entry/2013/07/02/183935
slim
https://github.com/slim-template/slim/blob/master/README.jp.md
ベンダープレフィックス
http://www.webcreatorbox.com/tech/sass-mixin/