Charts 如何在谷歌时间线图中突出显示当前日期？

我有一个谷歌时间表。我需要突出显示当前日期经过的块。我如何实现这些东西？这是我的密码。她：我需要突出显示通过当前日期的“F”时间线

function drawChart() {
          var container = document.getElementById('Gateways');
          var chart = new google.visualization.Timeline(container);
          var dataTable = new google.visualization.DataTable();
          dataTable.addColumn({ type: 'string', id: 'Room' });
          dataTable.addColumn({ type: 'string', id: 'Name' });
          dataTable.addColumn({ type: 'date', id: 'Start' });
          dataTable.addColumn({ type: 'date', id: 'End' });
          dataTable.addRows([
            [ '1', 'A', new Date(2011, 3, 30), new Date(2012, 2, 4) ],
            [ '1', 'B', new Date(2012, 2, 4),  new Date(2013, 3, 30) ],
            [ '1', 'C', new Date(2013, 3, 30), new Date(2014, 2, 4) ],
            [ '1', 'D', new Date(2014, 2, 4),  new Date(2015, 2, 4) ],
            [ '1', 'E', new Date(2015, 3, 30), new Date(2016, 2, 4) ],
            [ '1', 'F', new Date(2016, 2, 4),  new Date(2017, 2, 4) ],
            [ '1', 'G', new Date(2017, 2, 4),  new Date(2018, 2, 4) ],
            [ '1', 'H', new Date(2018, 2, 4),  new Date(2019, 2, 4) ],
            [ '1', 'I', new Date(2019, 2, 4),  new Date(2020, 2, 4) ],
            [ '1', 'J', new Date(2020, 2, 4),  new Date(2021, 2, 4) ]]);

          var options = {
            timeline: { showRowLabels: false },
            avoidOverlappingGridLines: false
          };

          chart.draw(dataTable, options);
        }