app.js

@@ -607,8 +607,8 @@ function clock() {
     timeCell.innerText = stats.time
 }
 
-function generate(piece) {
-    matrix.piece = piece || nextQueue.shift()
+function generate(piece=nextQueue.shift()) {
+    matrix.piece = piece
 
     if (matrix.piece.canMove(TRANSLATION.NONE)) {
         scheduler.setInterval(fall, stats.fallPeriod)
@@ -645,9 +645,14 @@ let playerActions = {
             matrix.piece.holdEnabled = false
             matrix.piece.locked = false
             matrix.piece.orientation = ORIENTATION.NORTH
-            let piece = holdQueue.piece
-            holdQueue.piece = matrix.piece
-            generate(piece)
+            if (holdQueue.piece) {
+                let piece = holdQueue.piece
+                holdQueue.piece = matrix.piece
+                generate(piece)
+            } else {
+                holdQueue.piece = matrix.piece
+                generate()
+            }
         }
     },
     

css/common.css

@@ -3,7 +3,7 @@
 }
 
 body {
-  background: linear-gradient(#212529, #14171a) fixed;
+  background: linear-gradient(#111315, #012) fixed;
 }
 
 .modal-content {