Flutter Unable to create corner curved color padding

Orange color corner curve padding not archive but here I get straight line only suggest any check my code..!

Widget build(Context context) {
            return Padding(
              padding: EdgeInsets.symmetric(vertical: 6.0, horizontal: 6.0),
              child: Card(
                elevation: 6.0,
                color: Colors.white,
                clipBehavior: Clip.hardEdge,
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(16.0),
                ),
                child: Container(
                  decoration: const BoxDecoration(
                    border: Border(
                      left: BorderSide(
                        color:  Colors.transparent,
                        width: 2.0,
                        style: BorderStyle.solid,
                      ),
                    ),
                  ),
                  padding: const EdgeInsets.all(18.0),
                  child: Column(
                    children: [],
                  ),
                ),
              ),
            );
          }

You could possibly use

            body: Padding(
              padding: const EdgeInsets.symmetric(vertical: 6.0, horizontal: 6.0),
              child: Card(
                elevation: 6.0,
                color: Colors.amber,
                clipBehavior: Clip.hardEdge,
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(20.0),
                ),
                child: Container(
                  height: 200,
                  width: MediaQuery.of(context).size.width,
                  margin: const EdgeInsets.only(left: 8), // 👈 This will specifiy the width of the curved border 
                  decoration: const BoxDecoration(
                      color: Colors.white,
                      borderRadius: BorderRadius.horizontal(
                        left: Radius.circular(20),
                      )),
                  padding: const EdgeInsets.all(18.0),
                  child: Column(
                    children: [],
                  ),
                ),
              ),
            ),

Output: