Best practice for displaying articles

I have an existing Angular app and want to use Confluence as both a full documentation site and in-app help. For the in-app help, I simply call the GET content endpoint, or so I thought. I can get the article body HTML, but none of the image or CSS assets are available. I then tried to pass expand=body.styled_view, which gives me several classes, but depends on a truckload of variables declared in ‘./imports/global’, which is not available.

What is the recommended way to display pages in other apps? Do I need to supply the styles myself? Use a different API? Use a specific library?