Change size and colour of SliverAppBar

ColorSliverAppBar.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  MyApp({Key key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final title = 'Floating App Bar';
    return MaterialApp(
      title: title,
      home: Scaffold(
        // No appbar provided to the Scaffold, only a body with a
        // CustomScrollView
        body: CustomScrollView(
          slivers: <Widget>[
            // Add the app bar to the CustomScrollView
            SliverAppBar(
              leading: IconButton(
                  icon: Icon(Icons.home),
                  tooltip: 'Click to Home Screen',
                  onPressed: () {
                    //  handle the press
                  }),
              // Provide a standard title
              title: Text(title),
              actions: <Widget>[
                IconButton(
                  icon: Icon(Icons.shopping_cart),
                  tooltip: 'Open shopping cart',
                  onPressed: () {
                    // handle the press
                  },
                ),
              ],
              brightness: Brightness.light,
              backgroundColor: Colors.transparent,
              iconTheme: IconThemeData(
                color: Colors.yellowAccent,
              ),
              textTheme: TextTheme(
                title:
                TextStyle(fontFamily: 'RobotoMono', color: Colors.deepOrange,
                    fontSize: 36.0),
              ),
              forceElevated: true,
              floating: true,
              pinned: true,
              // Make the initial height of the SliverAppBar larger than normal
              expandedHeight: 200,
            ),
            // Next, create a SliverList
            SliverList(
              // Use a delegate to build items as they're scrolled on screen.
              delegate: SliverChildBuilderDelegate(
                // The builder function returns a ListTile with a title that
                // displays the index of the current item
                (context, index) => ListTile(title: Text('Item #$index')),
                // Builds 1000 ListTiles
                childCount: 1000,
              ),
            ),
          ],
        ),
      ),
    );
  }
}