You will first have to build your project without scaling at 84x48 pixels.
Then you will need to open the index.html. Inside you should see a <style> tag somewhere. Inside that tag there should be a line that says: #canvas {
...
}

Add the following code inside the canvas.

transform: scale(10, 10);
transform-origin: top left;
image-rendering: pixelated;

And that should do the trick. If there it doesn't work then send me a screenshot and I will check it out.