webview/webview ? reverse-engineered prompt

Build me a tiny cross platform C and C++ library that lets an app show a simple desktop window with embedded web content, like a small browser view inside the app.

I want it to work on Linux, macOS, and Windows, using the native web engine on each platform, and I want both C and C++ APIs so I can create a window, set the title and size, load HTML or a URL, run it, and close it cleanly. It should also support calling JavaScript from C or C++, and calling back into the native code from JavaScript.

Please include a clean build setup, a few working examples, and a way to build it as a single header if possible. Make sure it feels easy to drop into another project, and add enough docs in the code so I can understand how to use it. If you need to check the latest platform docs while wiring up the native web views, go ahead and do that.