Angular app "loses" styling in production bundle

[EatonZ]

Steps to Reproduce:

There appears to be a problem when DevExtreme is bundled for production. It is easily reproducible:

1. npm start this attached application. This is a brand new app. No other added packages, DevExtreme setup instructions followed.
2. In the browser window that opens (for me this is Chrome), if you refresh the page a bunch of times (it doesn't happen every time), it will change between a white/broken background and a dark/normal background, and centered/broken tabs and left-aligned/normal tabs.

Results You Received:

Something is causing the app's body to lose all of the classes that should get added alongside dx-viewport, resulting in a white background and centered tabs.

Results You Expected:

If you remove --prod from ng serve in package.json, this issue does not occur, so it appears to be a production problem. Perhaps #14351 will fix?

Environment Details:

DevExtreme 20.1-stable
Angular 10.1.4
Windows 10
Chrome 85
Node 14.13.0

[EatonZ]

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