Set resolution to support retina display

.gitignore

@@ -1,3 +1,4 @@
 __pycache__
 *.swp
 *.pyc
+.idea/

static/app.js

@@ -1,5 +1,5 @@
 //Create the renderer
-const renderer = PIXI.autoDetectRenderer(256, 256);
+const renderer = PIXI.autoDetectRenderer(256, 256, {resolution: 2});
 renderer.view.style.position = 'absolute';
 renderer.view.style.display = 'block';
 renderer.autoResize = true;