Hi Ashpawan,

The appearance of splitter can be customized using css classes. You may modify the igspl_HSplitBar in ig_splitter.css and it will affect all splitters in application, or you may set custom class to the SplitterBar.CssClass property. Below is example to change alignment from center to left. You also may add any other attributes, like
padding-left:5px;

Note: the !important is used in order to override corresponding attribute which is set as inline style of splitterbar.

<style type="text/css">
    .collapseButtonCss { text-align: left !important; }
</style>
<ig:WebSplitter ID="WebSplitter1" runat="server" Height="300px" Orientation="Horizontal" Width="300px">
 <SplitterBar CssClass="collapseButtonCss">
 </SplitterBar>
  <Panes>
  <ig:SplitterPane runat="server" CollapsedDirection="NextPane">
  </ig:SplitterPane>
  <ig:SplitterPane runat="server">
  </ig:SplitterPane>
  </Panes>
</ig:WebSplitter>