Responsify right sidebar of dashboard

The sidebar of dashboard is not responsified. I used this code to workaround this:

@media all and (min-width: 960px) and (max-width: 5000px) {

  #dashboard div#dashboard_main {
    width: 75%;
  }

  #dashboard div#dashboard_sidebar {
    width: 15%;
  }

}

@media all and (max-width: 959px) {

  #dashboard {
    display: table;
  }

  #dashboard div#dashboard_main {
    display: table-footer-group;
    float: none;
  }

  #dashboard div#dashboard_sidebar {
    display: table-header-group;
  }

}