I have a CustomListView WebPart.Can created a special style for webpart. for example :A view style defines how list data is displayed within the body section of the page, which in a Boxed style includes everything that is contained within the box.
I found answer :
I took CoreV4.css located in C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\1033\STYLES\Themable and copied it locally, then attached it to my SharePoint page.
Save the copy to your SharePoint site in the Style Library or where you desire.
Open webpart and add your CSS reference: