gulpでruby-sassからnode-sassへ移行するときのハマりどころ ref: http://qiita.com/suisho/items/8e91c825c525ad17539b

application.scss

// 読み込まれない（エラー出ない）
@import "basic";            

// 読み込まれる
@import "sass/basic";

file0.txt

.foo{
  color: #12345
}

file1.txt

html { 
  filter: expression(document.execCommand("BackgroundImageCache",false, true));
}

file2.txt

@mixin box-sizing-border{
  @at-root{
    #{&}{
      box-sizing: border-box;

      *, *:before, *:after {
        box-sizing: inherit;
      }
    }
  }
}

file3.txt

@mixin box-sizing-border{
  @at-root{
    $selector: &
    #{$selector}{
      box-sizing: border-box;

      *, *:before, *:after {
        box-sizing: inherit;
      }
    }
  }
}

file4.txt

sass
├── _basic.scss
└── application.scss