The problem is the link to the files. Right now it shows it's trying to retrieve the CSS file from the following URL: https://192.168.1.220/css/app.css
However, it should use the same domain as your application: http://offline.vision/css/app.css
If you load your files you should add them like so
<link rel="stylesheet" href="/css/app.css">
This way it will retrieve the file relatively from the current domain. Then you will be able to resolve the CSS file.
You can see the proof here: http://offline.vision/css/app.css It will show you all the CSS correctly ;)