Ext生成的菜单，怎么让不同菜单有不同的背景色？

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大家好，下面是代码，图片中的5个菜单，我想让它有不同的底色。怎么设置啊？我不懂这里面是怎么实现的，求高手帮忙解答！谢谢！

 Ext.tip.QuickTipManager.init();
    var tree = Ext.create('Ext.panel.Panel', {
        xtype: 'layout-accordion',
        layout: 'accordion',
        region: 'west',
        title: '菜单导航',
        collapsible: true,
        animCollapse: true,
        split: true,
        width: 250,
        items: [{
            xtype: 'treepanel',
            width: 200,
            region: 'west',
            title: '双向转诊管理',
            renderTo: Ext.getBody(),
            store: treeStore,
            rootVisible: false,
            lines: false,
            useArrows: true,
            listeners: {
                itemclick: function (view, record, item, index, e) {
                    if (record.raw.text == '向上提交转诊单') {
                        if (Ext.getCmp("向上提交转诊单")) {
                            tab.setActiveTab('向上提交转诊单');
                            return;
                        }
                        new Ext.ux.Loader({
                            data: [
                                '/Scripts/ui_js/ReferralManager/upLoadReferralRecord.js'
                            ],
                            onsuccess: function () {
                                var upLoadReferralRecord = new Sehr.ReferralManager.upLoadReferralRecord();
                                tab.add({
                                    id: '向上提交转诊单',
                                    title: record.raw.text, closable: true,
                                    xtype: "container", layout: 'fit', items: upLoadReferralRecord.bodyPanel
                                });
                                tab.setActiveTab('向上提交转诊单');
                            }
                        });
                    }
                    if (record.raw.text == '向下提交转诊单') {
                        if (Ext.getCmp("向下提交转诊单")) {
                            tab.setActiveTab('向下提交转诊单');
                            return;
                        }
                        new Ext.ux.Loader({
                            data: [
                                '/Scripts/ui_js/ReferralManager/downLoadReferralRecord.js',
                                '/Scripts/ui_js/ReferralManager/ReferralRecordExamine.js'
                            ],
                            onsuccess: function () {
                                var downLoadReferralRecord = new Sehr.ReferralManager.downLoadReferralRecord();
                                tab.add({
                                    id: '向下提交转诊单',
                                    title: record.raw.text, closable: true,
                                    xtype: "container", layout: 'fit', items: downLoadReferralRecord.bodyPanel
                                });
                                tab.setActiveTab('向下提交转诊单');
                            }
                        });
                    }
                    if (record.raw.text == '转诊单管理（转入）') {
                        if (Ext.getCmp("转诊单管理（转入）")) {
                            tab.setActiveTab('转诊单管理（转入）');
                            return;
                        }
                        new Ext.ux.Loader({
                            data: [
                                '/Scripts/ui_js/ReferralManager/ReferralRecordTransfer.js',
                                '/Scripts/ui_js/ReferralManager/ReferralRecordTransferReceiver.js',
                                '/Scripts/ui_js/ReferralManager/ReferralRecordTransferRefuse.js',
                                '/Scripts/ui_js/ReferralManager/ReferralRecordExamine.js'
                            ],
                            onsuccess: function () {
                                var ReferralRecordTransfer = new Sehr.ReferralManager.ReferralRecordTransfer();
                                tab.add({
                                    id: '转诊单管理（转入）',
                                    title: record.raw.text, closable: true,
                                    xtype: "container", layout: 'fit', items: ReferralRecordTransfer.bodyPanel
                                });
                                tab.setActiveTab('转诊单管理（转入）');
                            }
                        });
                    }
                    if (record.raw.text == '转诊单管理（转出）') {
                        if (Ext.getCmp("转诊单管理（转出）")) {
                            tab.setActiveTab('转诊单管理（转出）');
                            return;
                        }
                        new Ext.ux.Loader({
                            data: [
                                '/Scripts/ui_js/ReferralManager/ReferralRecordRollOut.js',
                                '/Scripts/ui_js/ReferralManager/ReferralRecordExamine.js'
                            ],
                            onsuccess: function () {
                                var ReferralRecordRollOut = new Sehr.ReferralManager.ReferralRecordRollOut();
                                tab.add({
                                    id: '转诊单管理（转出）',
                                    title: record.raw.text, closable: true,
                                    xtype: "container", layout: 'fit', items: ReferralRecordRollOut.bodyPanel
                                });
                                tab.setActiveTab('转诊单管理（转出）');
                            }
                        });
                    }
                    if (record.raw.text == '系统维护') {
                        if (Ext.getCmp("系统维护")) {
                            tab.setActiveTab('系统维护');
                            return;
                        }
                        new Ext.ux.Loader({
                            data: [
                                '/Scripts/ui_js/ReferralManager/SystemMaintain.js',
                                '/Scripts/ui_js/ReferralManager/SystemMaintainAdd.js'
                            ],
                            onsuccess: function () {
                                var SystemMaintain = new Sehr.ReferralManager.SystemMaintain();
                                tab.add({
                                    id: '系统维护',
                                    title: record.raw.text, closable: true,
                                    xtype: "container", layout: 'fit', items: SystemMaintain.bodyPanel
                                });
                                tab.setActiveTab('系统维护');
                            }
                        });
                    }
                }
            }
        }]
    });

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