background color in line graph

private void chart_bind()
{
  DataTable dt = new DataTable();
  try
  {
      dt = GetData();

      str.Append(@"<script type=text/javascript> google.load( *visualization*, *1*, {packages:[*corechart*]});
      google.setOnLoadCallback(drawChart);
      function drawChart() {
      var data = new google.visualization.DataTable();
      data.addColumn('string', 'time');
      data.addColumn('number', 'price');
      data.addRows(" + dt.Rows.Count + ");");

      Int32 i;

      for (i = 0; i <= dt.Rows.Count - 1; i++)
      {
          str.Append("data.setValue( " + i + "," + 0 + "," + "'" + dt.Rows[i]["time"].ToString() + "');");
          str.Append("data.setValue(" + i + "," + 1 + "," + dt.Rows[i]["price"].ToString() + ") ;");
      }

      str.Append("   var chart = new google.visualization.LineChart(document.getElementById('chart_div'));");

      str.Append(" chart.draw(data, {width: 660, height: 300,title: '',");
      str.Append("hAxis: {title: 'Time', titleTextStyle: {color: 'green'}}");
      str.Append("}); }");
      str.Append("</script>");
      lt.Text = str.ToString().TrimEnd(',').Replace('*', '"');
  }
  catch
  { }
}