Repository: flutter
Issue: [flutter_adaptive_scaffold] Weird line appears between body and secondary body when background color is applied.
Labels: package,team-ecosystem,has reproducible steps,P3,p: flutter_adaptive_scaffold,found in release: 3.7,found in release: 3.10,triaged-ecosystem

### Is there an existing issue for this?

- [X] I have searched the [existing issues](https://github.com/flutter/flutter/issues)
- [X] I have read the [guide to filing a bug](https://flutter.dev/docs/resources/bug-reports)

### Steps to reproduce

Run the Code sample.

### Expected results

The line between pages (body and secondary body) should not appear.

### Actual results

 If there is a color applied in background a weird line shows between two pages (body and secondary body)

### Code sample

<details><summary>Code sample</summary>

The issue can be replicated via the below example code.
```dart
import 'package:flutter/material.dart';
import 'package:flutter_adaptive_scaffold/flutter_adaptive_scaffold.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'AdaptiveNavigation weird line',
      home: AdaptiveNavigation(),
    );
  }
}

class AdaptiveNavigation extends StatefulWidget {
  const AdaptiveNavigation({super.key});

  @override
  State<StatefulWidget> createState() => _AdaptiveNavigationState();
}

class _AdaptiveNavigationState extends State<AdaptiveNavigation> {
  @override
  Widget build(BuildContext context) {
    return Container(
      /// If there is a color applied in background a weird line shows between two pages
      /// also the transition looks weird also
      color: Colors.black,

      child: AdaptiveLayout(
        // ratio of body and secondaryBody
        // refer: https://pub.dev/packages/flutter_adaptive_scaffold
        bodyRatio: 0.45,
        body: SlotLayout(
          config: <Breakpoint, SlotLayoutConfig>{
            Breakpoints.standard: SlotLayout.from(
              key: const Key('body'),
              builder: (_) => const Scaffold(
                backgroundColor: Color(0xFFF6F6F6),
                body: Center(child: Text('body')),
              ),
            ),
          },
        ),
        // this occupies only the right half of the screen in tablet-landscape view
        secondaryBody: SlotLayout(
          config: <Breakpoint, SlotLayoutConfig>{
            // shows in tablet-landscape view
            Breakpoints.large: SlotLayout.from(
              key: const Key('secondayBody'),
              builder: (_) => const Scaffold(
                backgroundColor: Color(0xFFF6F6F6),
                body: Center(child: Text('secondary body')),
              ),
            )
          },
        ),
      ),
    );
  }
}

```

</details>


### Screenshots or Video

<details>
<summary>Screenshots / Video demonstration</summary>

![image](https://user-images.githubusercontent.com/38380040/234786439-af21588c-874c-40fc-8050-9cdd6134f4c5.png)

</details>


### Logs

_No response_

### Flutter Doctor output

<details><summary>Doctor output</summary>

```console
[√] Flutter (Channel stable, 3.7.12, on Microsoft Windows [Version 10.0.22621.1635], locale en-US)
    • Flutter version 3.7.12 on channel stable at C:\Users\Harish\fvm\versions\stable
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 4d9e56e694 (9 days ago), 2023-04-17 21:47:46 -0400    • Engine revision 1a65d409c7
    • Dart version 2.19.6
    • DevTools version 2.20.1

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
    • Android SDK at C:\Users\Harish\AppData\Local\Android\sdk
    • Platform android-33-ext4, build-tools 33.0.2
    • Java binary at: C:\Program Files\Android\Android Studio1\jbr\bin\java
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-9586694)
    • All Android licenses accepted.

[X] Chrome - develop for the web (Cannot find Chrome executable at .\Google\Chrome\Application\chrome.exe)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.

[X] Visual Studio - develop for Windows
    X Visual Studio not installed; this is necessary for Windows development.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the "Desktop development with C++" workload, including all of its default components

[!] Android Studio (version 2022.1)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    X Unable to determine bundled Java version.
    • Try updating or re-installing Android Studio.

[√] Android Studio (version 2022.2)
    • Android Studio at C:\Program Files\Android\Android Studio1
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-9586694)

[√] VS Code (version 1.77.3)
    • VS Code at C:\Users\Harish\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.62.0

[√] Connected device (3 available)
    • SM T550 (mobile)  • 192.168.1.44:5555 • android-arm    • Android 7.1.1 (API 25)
    • Windows (desktop) • windows           • windows-x64    • Microsoft Windows [Version 10.0.22621.1635]
    • Edge (web)        • edge              • web-javascript • Microsoft Edge 112.0.1722.58

[√] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 3 categories.
```

</details>