Tweak play button after recent changes

Author: microbit-matt-hillsdon

src/simulator.html

@@ -35,8 +35,8 @@
       }
       .play-button svg {
         position: absolute;
-        width: 47%;
-        height: 47%;
+        width: 45%;
+        height: 45%;
       }
       .play-button-container {
         position: absolute;