markArea虚线echarts 折线配置项内容和展示

想让 markarea被虚线包围起来怎么操作

      option = {
    title: {
        text: '一天用电量分布',
        subtext: '纯属虚构'
    },
    tooltip: {
        trigger: 'axis',
        axisPointer: {
            type: 'cross'
        }
    },
    toolbox: {
        show: true,
        feature: {
            saveAsImage: {}
        }
    },
    xAxis:  {
        type: 'category',
        boundaryGap: false,
        data: ['00:00', '01:15', '02:30', '03:45', '05:00', '06:15', '07:30', '08:45', '10:00', '11:15', '12:30', '13:45', '15:00', '16:15', '17:30', '18:45', '20:00', '21:15', '22:30', '23:45']
    },
    yAxis: {
        type: 'value',
        axisLabel: {
            formatter: '{value} W'
        },
        axisPointer: {
            snap: true
        }
    },
    visualMap: {
        show: false,
        dimension: 0,
        pieces: [{
            lte: 6,
            color: 'green'
        }, {
            gt: 6,
            lte: 8,
            color: 'red'
        }, {
            gt: 8,
            lte: 14,
            color: 'green'
        }, {
            gt: 14,
            lte: 17,
            color: 'red'
        }, {
            gt: 17,
            color: 'green'
        }]
    },
    series: [
        {
            name:'用电量',
            type:'line',
            smooth: true,
            data: [300, 280, 250, 260, 270, 300, 550, 500, 400, 390, 380, 390, 400, 500, 600, 750, 800, 700, 600, 400],
            markArea: {
                data: [ [{
                    name: '早高峰',
                    xAxis: '07:30',
                    itemStyle:{
                        normal:{
                            color:'none',
                            lineStyle:{
                                width:2,
                                type:'dotted'
                            }
                        }
                    },
                    label: {
                        show: true,
                        position: 'inside',
                        color: 'black',
                        rotate: 0,
                        formatter: "橙色预警"
                    }
                }, {
                    xAxis: '10:00',
                    y:'50%'
                }]]
            }
        }
    ]
};