Use more specific class names: grouped -> btn-grouped

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Refactor scss

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
 Merge branch 'refactor_css' into 'master'

Refactor Css
Revert "set layout margin-bottom 50px"

Because .content class used in several other places and this change add
unnecessary margint ot it

This reverts commit f8807281ee591ac00462c1f60de0a01392b906e4.