Turn off transparency 

@@ -22,6 +22,9 @@
     title              => 'Product Sales',
     y_label            => 'Units Shipped (Millions)',
     x_label            => 'Product Sales by Year',
+    transparent        => 0,
+    bgclr              => '#fffd48',
+    boxclr             => 'white',
     dclrs              => ['#ff782a', '#6daa3a', '#4d7296'],
 ) or die $graph->error;