Are you viewing a file on your computer in your browser without a server? The url would look something like this: file://link/to/your/page.
This might be causing one of the below issues:
App not loading on page
If you are not seeing your App at all when opening your HTML file in your web browser, don't panic. This may be an issue with the security settings of your browser. Try using the iFrame code instead so you can preview your site with the App on it.
App is cut off on page
The powr.js file is not able to resize the app using the file:// protocol, so your app might appear cut in half.
Try viewing the page through http:// using a web server. If you have a local server, view the file through your server. Or, move the file to your hosting provider and then view it in a browser.