extjs 表頭居中，數據靠左的寫法

var queryCm = new Ext.grid.ColumnModel([
      new Ext.grid.RowNumberer(),
      {header:'市分公司編碼',dataIndex:'city_id',hidden:true},
      {header:'<div style="text-align:center">市分公司</div>',dataIndex:'city_name',width:100,sortable:true,renderer:showTip,align:'left'},
      {header:'營業部編碼',dataIndex:'dept_id',hidden:true},
      {header:'營業部',dataIndex:'dept_name',width:100,sortable:true,renderer:showTip,align:'center'},
      {header:'sim卡類型編碼',dataIndex:'sim_type_id',width:100,sortable:true,renderer:showTip,align:'center'},
      {header:'SIM卡類型名稱',dataIndex:'sim_type_name',width:150,sortable:true,renderer:showTip,align:'left'},
      {header:'未銷售卡數量',dataIndex:'unsell_sim_count',sortable:true,width:100,align:'right'},
      {header:'預銷售卡數量',dataIndex:'presell_sim_count',sortable:true,width:100,align:'right'},
      {header:'已使用卡數量',dataIndex:'sold_sim_count',sortable:true,width:100,align:'right'},
      {header:'廢卡量',dataIndex:'bad_count',sortable:true,width:100,align:'right'}
     ]);