_buildHeader.dart

  Widget _buildHeader() {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 80.0, horizontal: 24.0),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisAlignment: MainAxisAlignment.start,
        children: <Widget>[
          Text(
            'Explore',
            style: TextStyle(fontSize: 24.0, fontWeight: FontWeight.w600),
          ),
          SizedBox(
            height: 5.0,
          ),
          Text(
            'new amazing countries',
            style: TextStyle(fontSize: 20.0, fontWeight: FontWeight.w100),
          )
        ],
      ),
    );
  }