remove border in background in flutter - flutter

Question

I'm confused how to make the colored border cut off, when I meet the word "Month", I tried with BoxDecoration(color: Colors.transparent), but it doesn't produce anything, the border still doesn't get cut.
like the following :
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
#override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Container(
decoration: BoxDecoration(color: Colors.blue),
child: Center(
child: Container(
width: 120,
height: 110,
decoration: BoxDecoration(color: Colors.pink),
child: Stack(
children: [
Positioned(
bottom: 0,
child: Container(
height: 55,
width: 120,
decoration: BoxDecoration(
color: Colors.green,
borderRadius: BorderRadius.all(Radius.circular(10)),
border: Border.all(width: 2, color: Colors.white),
),
),
),
Positioned(
left: (120 - 50) / 2,
top: 45,
child: Container(
width: 50,
height: 15,
decoration:
BoxDecoration(color: Colors.black.withOpacity(0.1)),
child: Center(
child: Text("Month"),
),
),
),
],
),
),
),
)),
);}}
I want a look like this:
Please for the guidance, Thank you

Answer 1

A sample quick trick to have the effect you want is to set the background color for your positioned text as the same as your pink container:
child: Container(
width: 50,
height: 15,
padding: const EdgeInsets.all(5.0) <- with this too
decoration:
BoxDecoration(color: Colors.pink,), <- here
child: Center(
child: Text("Month"),
),

Answer 2

try this
Scaffold(
body: Stack(
children: <Widget>[
Container(
width: double.infinity,
height: 200,
margin: EdgeInsets.fromLTRB(20, 20, 20, 10),
padding: EdgeInsets.only(bottom: 10),
decoration: BoxDecoration(
color: Colors.green,
border: Border.all(width: 2, color: Colors.white),
borderRadius: BorderRadius.circular(15),
shape: BoxShape.rectangle,
),
),
Positioned(
left: 100,
top: 12,
child: Container(
padding: EdgeInsets.only(bottom: 10, left: 10, right: 10),
color: Colors.black.withOpacity(0.1),
child: Text(
'Month',
),
),
),
],
),
)