Transparent color of OpenContainer widget (from animations package is grey instead of transparent

I am writing a UI, where the background has an image, on top of that there will be transparent Cards in a listView. On clicking on one of those, it will open the details page. I want to add OpenContainer animation for the transition to the details page.

But after adding OpenContainer (which has a default color of white in closed state), i couldn’t make those cards transparent again. Even if i set closedColor to Colors.transparent, it is producing grey instead of transparent.

I have repreoduced the issue in simple way.

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.pinkAccent,
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: ListView(
        children: [
          testContainer(),
          testContainer(),
          testContainer(),
          testContainer(),
          testContainer(),
          testContainer(),
        ],
      ),
    );
  }

  OpenContainer<Object> testContainer() {
    return OpenContainer(
      closedColor: Colors.transparent,
      closedBuilder: (BuildContext context, void Function() openBuilder) {
        return Container(
          height: 35,
          width: double.infinity,
          color: Colors.transparent,
          child: const Center(child: Text("hello")),
        );
      },
      openBuilder: (BuildContext context,
          void Function({Object? returnValue}) closeBuilder) {
        return Container(
          height: 300,
          width: double.infinity,
          child: const Center(child: Text("WW")),
        );
      },
    );
  }
}

After adding OpenContainer

Expected

>Solution :

Include closedElevation: 0,.

return OpenContainer(
  closedColor: Colors.transparent,
  closedElevation: 0,

More about OpenContainer .