Themes improvements

android/assets/themes/bandw.theme

@@ -2,7 +2,7 @@
     "name": "Black et White",
     "price": 20,
     "colors": {
-        "background": "0a0a0aff",
+        "background": "000000ff",
         "foreground": "202020ff",
         "buttons": [
             "f0f0f0ff",
@@ -10,7 +10,7 @@
             "f0f0f0ff",
             "f0f0f0ff"
         ],
-        "empty_cell": "000000ff",
+        "empty_cell": "202020ff",
         "cells": [
             "f2f2f2ff", "f2f2f2ff", "f2f2f2ff",
             "f2f2f2ff", "f2f2f2ff", "f2f2f2ff", "f2f2f2ff",

android/assets/themes/underwater.theme

@@ -12,7 +12,7 @@
         ],
         "empty_cell": "0066ffff",
         "cells": [
-            "37c871ff", "2ad4ffff", "0000d4ff",
+            "37c871ff", "2ad4ffff", "00ffeeff",
             "00ffccff", "5599ffff", "87cddeff", "80b3ffff",
             "00ff66ff", "00d4aaff"
         ],