how to modify the css of gwt-TabLayoutPanelContent

[tong123123]

I remove the tab bar by passing 0px in the constructor of TabLayoutPanel, but then I found there is a outline surround the datagrid <thead> inside (as shown in the attachment), I use IE8 debug mode and found that this is due to the
.gwt-TabLayoutPanel .gwt-TabLayoutPanelContent{
   padding-top:6px;
   .......
}

I want to set the padding of gwt-TabLayoutPanel .gwt-TabLayoutPanelContent to 0px for this TabLayoutPanel only, I try to use \
TabLayoutPanel.addStyleNme("nopaddingcssclass");

but no use.
so how to modify the padding properties of .gwt-TabLayoutPanel .gwt-TabLayoutPanelContent for this TabLayoutPanel only?

[tong123123]

if modifying the standard.css, it will affect all the tablayoutpanel, it is difficult to change just one tablayoutpanel
.gwt-TabLayoutpanel .gwt-TabLayoutPanelContent
css class padding property, right?