Auto-scale game canvas

src/frontend/game.js

@@ -22,6 +22,10 @@ class Game {
       type: Phaser.AUTO,
       width: width,
       height: height,
+      scale: {
+        mode: Phaser.Scale.FIT,
+        autoCenter: Phaser.Scale.CENTER_BOTH
+      },
       scene: TestScene
     };