MVC3中使用的jqGrid的背景颜色怎么修改

就是改变上边蓝色的颜色。
UsersGrid = new JQGrid
            {
                Columns = new List<JQGridColumn>()
                                 {
                                     new JQGridColumn { DataField = "UserID", 
                                                        // always set PrimaryKey for Add,Edit,Delete operations
                                                        // if not set, the first column will be assumed as primary key
                                                        PrimaryKey = true,
                                                        Editable = false,
                                                        HeaderText="序号", 
                                                        Width = 50,
                                                        CssClass="_color"  
                                                       },
                                     new JQGridColumn { DataField = "UserName",
                                                        Editable = true,
                                                        Width = 100,
                                                        DataFormatString = "{0:d}" ,
                                                        HeaderText="用户名"}, 
                                     new JQGridColumn { DataField = "Password",
                                                        Editable = true,
                                                        Width = 100 ,
                                                        HeaderText="口令"},
                                     new JQGridColumn { DataField = "Description",
                                                        Editable = true,
                                                        Width = 75 ,
                                                        HeaderText="描述"}
                                 },
                                 //怎么设置背景颜色？
                Width = Unit.Pixel(640) ,     
                Height = Unit.Pixel(500)      
            };
            
            UsersGrid.ToolBarSettings.ShowRefreshButton = true;
MVC jqGrid

补充：.NET技术 ,  C#