add meta theme-color - closes #5603

app/views/base/layout.scala

@@ -23,6 +23,9 @@ object layout {
       s"""<meta http-equiv="Content-Security-Policy" content="$csp">"""
     }
     def metaCsp(csp: Option[ContentSecurityPolicy])(implicit ctx: Context): Frag = metaCsp(csp getOrElse defaultCsp)
+    def metaThemeColor(implicit ctx: Context): Frag = raw {
+      s"""<meta name="theme-color" content="${ctx.pref.themeColor}">"""
+    }
     def pieceSprite(implicit ctx: Context): Frag = pieceSprite(ctx.currentPieceSet)
     def pieceSprite(ps: lila.pref.PieceSet): Frag =
       link(id := "piece-sprite", href := assetUrl(s"piece-css/$ps.css"), tpe := "text/css", rel := "stylesheet")
@@ -118,6 +121,7 @@ object layout {
         charset,
         viewport,
         metaCsp(csp),
+        metaThemeColor,
         if (isProd && !isStage) frag(
           st.headTitle(fullTitle | s"$title • lichess.org")
         )

modules/pref/src/main/Pref.scala

@@ -52,6 +52,8 @@ case class Pref(
   def realTheme3d = Theme3d(theme3d)
   def realPieceSet3d = PieceSet3d(pieceSet3d)
 
+  def themeColor = if (transp || dark) "#2e2a24" else "#dbd7d1"
+
   def realSoundSet = SoundSet(soundSet)
 
   def coordColorName = Color.choices.toMap.get(coordColor).fold("random")(_.toLowerCase)