ASPX

<toolkit:TabContainer CssClass="ajax__tab_Default" runat="server" ID="Tabs">
            <toolkit:TabPanel EnableTheming="false" runat="Server" Width="300px" ID="phlInfo">
                <HeaderTemplate>
                    <span class="btnNormal">Panel1</span>
                </HeaderTemplate>
                <ContentTemplate>
                    Content
                </ContentTemplate>
            </toolkit:TabPanel>
            <toolkit:TabPanel runat="Server" ID="phlFlowLog">
                <HeaderTemplate>
                    <span class="btnNormal">panel2</span>
                </HeaderTemplate>
                <ContentTemplate>
                    Panel2
                </ContentTemplate>
            </toolkit:TabPanel>
            <toolkit:TabPanel runat="Server" ID="phlFlowFigure">
                <HeaderTemplate>
                    <span class="btnNormal">Panel3</span>
                </HeaderTemplate>
                <ContentTemplate>
                    panel3
                </ContentTemplate>
            </toolkit:TabPanel>
        </toolkit:TabContainer>

CSS:

.ajax__tab_Default .ajax__tab_header
{
    padding:12px 0 0 0px;
    height: 20px;
    background:#EDEDED url(Icons/TabLine.gif) repeat-x bottom;
}
.ajax__tab_Default .ajax__tab_outer
{
}
.ajax__tab_Default .ajax__tab_inner
{
}
.ajax__tab_Default .ajax__tab_tab
{
    margin-left:10px;
    text-align: center;
    padding: 5px 5px 3px 10px;
    font-size: 12px;
    width:100px;
    cursor:pointer;
}

.ajax__tab_Default .ajax__tab_hover .ajax__tab_outer ,.ajax__tab_Default .ajax__tab_active .ajax__tab_outer

注意事项：
1、tab控件在UpdatePanel中时，如果tab在页面初始时不显示，则会出现小BUG