Question

compass defaultly not getnerate css items ,but I want to keep these items alway,because sometime I can use firebug code these empty items .any way to keep them, how to set?

Answer 1

There is a quick solution: added a comment in each non-deletable property to keep.

.help_center {
  /*! keep */
  .nav {
    /*! keep */
  }
}

The documentation says:

When the first letter of a comment is !, the comment will be interpolated and always rendered into css output even in compressed output modes. This is useful for adding Copyright notices to your generated CSS.