appBar: PreferredSize( preferredSize: Size.fromHeight(90), child: AppBar( title: Text( 'About This App', style: TextStyle(fontSize: 28), ), centerTitle: true, backgroundColor: Color(0xffbf360c), elevation: 10, shadowColor: Color(0xff3f51b5), shape: RoundedRectangleBorder( borderRadius: BorderRadius.only( bottomLeft: Radius.circular(25), bottomRight: Radius.circular(25), ), ), ), ),