how to place one container over another container - Flutter

I am trying to do this particular design for the Login page.

But the result I got it is on below:

The code I tried is:

               Stack(
                      fit: StackFit.passthrough,
                      children: [
                        Container(height: 2, color: Colors.grey),
                        Positioned(
                          child: Center(
                            child: Transform.rotate(
                              alignment: Alignment.center,
                              angle: 45,
                              child: Container(
                                height: 18,
                                width: 18,
                                color: colorController.primaryColor.value,
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),

Line Widget (Container with color ) size is 2 that's cause result mismatch from what you want

fix it to this

 Stack(
   fit: StackFit.passthrough,
   children: [
     const SizedBox(
       height: 18,
       child: Divider(
         color: Colors.grey,
         height: 2,
         thickness: 2,
       ),
     ),
     Positioned(
       child: Center(
         child: Transform.rotate(
           alignment: Alignment.center,
           angle: 40,
           child: Container(
             height: 18,
             width: 18,
             color: Colors.blue,
           ),
         ),
       ),
     )
   ],
 ),