Change 'current' to 'playing'.

assets/css/queue.css.sass

@@ -1,2 +1,2 @@
-#queue .current
+#queue .playing
   font-weight: bold

models/song.rb

@@ -1,17 +1,18 @@
 require './models/mpd_connection'
 
-class Song < Struct.new(:artist, :album, :title, :current)
+class Song < Struct.new(:id, :artist, :album, :title, :playing)
 
-  def initialize(song, current: false)
+  def initialize(song, playing: false)
     @song = song
+    self.id = song.songid
     self.artist = song.artist
     self.album = song.album
     self.title  = song.title
-    self.current = current
+    self.playing = playing
   end
 
   def self.queue
     current_song = MPDConnection.mpd.status[:songid]
-    MPDConnection.mpd.queue.map { |song| self.new(song, current: (song.id == current_song)) }
+    MPDConnection.mpd.queue.map { |song| self.new(song, playing: (song.id == current_song)) }
   end
 end

views/index.erb

@@ -17,7 +17,9 @@
       <h2>Queue</h2>
       <ul id="queue">
       {{#each controller}}
-        <li {{bindAttr class="current"}}>{{ artist }} - {{ title }}</li>
+        <li {{bindAttr class="playing"}}>{{ artist }} - {{ title }}</li>
+      {{else}}
+        <li>Play queue empty</li>
       {{/each}}
       </ul>
     </script>