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In order to modify the appearance of your TabStrip you would have to create your own skin and styles sheet. We have a tutorial on how to create custom skins for your TabStrip. Please look at creating a custom TabStrip skin
. In the case of working with Sitefinity you will have to do the following:
1. Open your project in Visual Studio;
2. Open App_Themes folder;
3. Open the theme folder in which you want to modify the appearance of TabStrip(e.g. Orange with left sidebar);
4. Copy and paste the skin file and the Css file in the App_Themes
From there you can follow the steps described in the "Create A Custom Skin" tutorial.
Your .skin file should look something like this:
|<%@ Register TagPrefix="telerik" Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" %>
Please look at the image attached to see where the .skin file and the Css files are copied.
All the best,
the Telerik team