As requested by @MrTimscampi + theme adjustement

src/themes/appletv/theme.css

@@ -43,7 +43,9 @@ html {
 }
 
 .backgroundContainer,
-.dialog {
+.dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu {
     background: #d5e9f2;
     -webkit-background-size: 100% 100%;
     background-size: 100% 100%;

src/themes/blueradiance/theme.css

@@ -42,6 +42,8 @@ html {
 }
 
 .dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu,
 html {
     background-color: #033361;
 }

src/themes/dark/theme.css

@@ -36,6 +36,8 @@ html {
 
 .backgroundContainer,
 .dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu,
 html {
     background-color: #101010;
 }

src/themes/light/theme.css

@@ -51,7 +51,9 @@ html {
     background-color: rgba(255, 255, 255, 0.8);
 }
 
-.dialog {
+.dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu {
     background-color: #f0f0f0;
 }
 

src/themes/purplehaze/theme.css

@@ -37,6 +37,8 @@ html {
 }
 
 .dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu,
 html {
     background-color: #230c33;
 }

src/themes/wmc/theme.css

@@ -48,7 +48,9 @@ html {
 }
 
 .backgroundContainer,
-.dialog {
+.dialog,
+.nowPlayingPlaylist,
+.nowPlayingContextMenu {
     background: -webkit-gradient(linear, left top, left bottom, from(#0f3562), color-stop(#1162a4), to(#03215f));
     background: -webkit-linear-gradient(top, #0f3562, #1162a4, #03215f);
     background: -o-linear-gradient(top, #0f3562, #1162a4, #03215f);