我使用的是syncfusion圆形图，我设置了圆环图类型，在标题、图表和图例之间给予了额外的空格。如何减少它们之间的额外空格？

下面是设置这些代码

Expanded(
            child: Card(
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(8), // if you need this
                side: BorderSide(
                  color: Colors.grey.withOpacity(0.2),
                  width: 1,
                ),
              ),
              child: Container(
                transform: Matrix4.translationValues(-15.0, 0.0, 00.0),
                child: SfCircularChart(
                  margin: EdgeInsets.symmetric(vertical: 8.0,horizontal: 12.0),
                  title: ChartTitle(
                    text: 'Today\'s Employee\'s Attendance',
                    textStyle: TextStyle(
                        color: Color(0xff15728a),
                        fontWeight: FontWeight.bold,
                        fontSize: 8.0),
                  ),
                  tooltipBehavior: _tooltipBehavior,
                  legend: Legend(
                      position: LegendPosition.bottom,
                      isVisible: true,
                      isResponsive:true,
                      overflowMode: LegendItemOverflowMode.wrap),
                  series: <CircularSeries>[
                    DoughnutSeries<AttendanceData, String>(

                      dataSource: attendance,
                      pointColorMapper:(AttendanceData data,_)=>data.colors,
                      xValueMapper: (AttendanceData data, _) =>
                      data.status,
                      yValueMapper: (AttendanceData data, _) =>
                      data.value,
                      dataLabelSettings:
                      DataLabelSettings(isVisible: true),
                      enableTooltip: true,
                    ),
                  ],
                ),
              ),
            ),
          ),