Improve theme support.

library.json

@@ -3,7 +3,7 @@
   "description": "See how many cards you can remember!",
   "majorVersion": 1,
   "minorVersion": 1,
-  "patchVersion": 0,
+  "patchVersion": 1,
   "runnable": 1,
   "author": "Amendor AS",
   "license": "MIT",

memory-game.css

@@ -24,6 +24,8 @@ html .h5p-memory-game > ul {
   outline: none;
   position: relative;
   margin: 1em;
+  padding: 0;
+  background: transparent;
   -webkit-perspective: 400px;
   -moz-perspective: 400px;
   perspective: 400px;
@@ -175,4 +177,4 @@ html .h5p-memory-game > ul {
   background: #f0f0f0;
   width: 100px;
   height: 100px;
-}
+}