Phaser 2 PWA Scaling Issue

[vastron]

Hello,

I created a pwa with Phaser 2, following this tutorial https://phaser.io/news/2018/10/progressive-web-apps-tutorial. 

I face a problem with how the game scales on mobile.

In my game I use these Phaser 2 methods:

game.scale.scaleMode = Phaser.ScaleManager.SHOW_ALL;
game.scale.pageAlignHorizontally = true;
game.scale.pageAlignVertically = true;

When I click the localhost link in my mobile,

 the game is way too big and when I 'download' it to act like an app, it gets really shaky at first, scaling up and down until it settles to the correct size. 

The game dimensions are 1280x720.

It looked very nice before I converted it to a PWA.

I did an audit for a PWA in Chrome's dev tools and it showed this notification:

The viewport size is 1280px, whereas the window size is 412px.

Do you have any idea on how to fix this issue?