#login, .ad_here {
  display: block;
}
#authorized, .player, .set-playlist, .dynamic-playlist {
  display: none;
}

.album {
  .art .button-container {
    display: none; 
  }
  .tracks tr:hover {
    .s-duration {
      display: block;
    }
    .s-add {
      display: none;
    }
  }
}

body.authorized {
  .album {
    .art .button-container {
      display: block; 
    }
    .tracks tr:hover {
      .s-duration {
        display: none;
      }
      .s-add {
        display: block;
      }
    }
  }
  .set-playlist, .dynamic-playlist {
    display: block;
  }
  #login, .ad_here {
    display: none;
  }
  #authorized, .player {
    display: block;
  }
}