Creating a Custom Skin
Developers who want to create a custom skin for one or more Telerik control, have the following options:
Use the Telerik ThemeBuilder for ASP.NET AJAX application (for Lightweight RenderMode skins)
Use the Visual Style Builder tool (discontinued since 2016).
Take an embedded skin and make changes to it until you have the desired look
Create a custom skin from scratch
In most cases the last option is an unnecessary overhead, unless you need to create a skin, which is totally unique in terms of look and feel, and dimensions. In order to create a custom skin from scratch, you need a better understanding for the control's HTML output and CSS classes.
After you create the custom skin you will need to register it on the page where it will be used.
Telerik ThemeBuilder application
This is an easy to use application that enables you to customize the default look and feel. It can be used to customize only skins for Lightweight RenderMode.
Read the documentation for illustration and examples on how to create a custom theme.
Launch the application.
The Theme Builder application can be used to create or modify themes used in Lightweight RenderMode
Visual Style Builder
If you would like to modify a skin that will be used in Classic RenderMode you can use the StyleBuilder tool.
read the tool overview on the Telerik website
The Classic render mode is in maintenance mode since Q3 2015 and the Visual Style Builder tool, which produces skins for the Classic rendering only, is in maintenance since May 2016. We recommend using the Lightweight render mode and the provided Telerik ThemeBuilder for ASP.NET AJAX tool.
Create a Custom Skin From an Existing Embedded Skin
Here is a list of the required steps to perform:
Pick a built-in skin which looks similar to your requirements. For example, the "Telerik" skin of RadColorPicker.
Copy the "Common" and "Telerik" folders from "C:\Program Files\Progress\UI for ASP.NET AJAX RX YYYY\Skins" into your application folder. (If you have installed Telerik® UI for ASP.NET AJAX from a ZIP file, the /Skins/ folder is in the ZIP archive root.) You can delete any unnecessary CSS files or folders inside the "Telerik" folder. Only the ColorPicker folder and ColorPicker.Telerik.css are needed for this example.
Pick a name for your skin. We will use "MySkin" for the example.
Rename the "Telerik" folder to "MySkin". Renaming is optional but will imply that the skin is a custom skin. Renaming the skin is required if you intend to use it together with an embedded skin with the same name on the same page.If you rename the folder it is a good idea to rename the CSS file as well, for example "ColorPicker.MySkin.css"
A similar CSS selector is used in all skins. The naming convention is .Rad[Control]_[Skin]. For example .RadSlider_Inox or .RadColorPicker_Telerik. If you rename an existing skin, you must rename all skin suffixes in the CSS class names as follows .ClassName_Telerik --> .ClassName_MySkin.
Register the CSS file in your page. See the Skin Registration topic for more details.
Set the Skin property of your RadColorPicker to "MySkin". Then set the EnableEmbeddedSkins property to false.
If you don't set EnableEmbeddedSkins to false an exception will be thrown saying that RadColorPicker cannot find an embedded skin named "MySkin". For more information you can check the How skins work and Skin registration topics.
Modify CSS rules to match your visual requirements. Save the CSS file.
Run the project. If all steps are performed correctly the RadColorPicker should use your newly defined skin.
Create a Custom Skin dll
As of 2021, the SkinAssemblyBuilder is discontinued and not supported. Since it used to work for Classic render mode skins, it was not compatible with the skin files produced by the Progress SASS ThemeBuilder for ASP.NET AJAX app.
To create a Skins Assembly, you can follow the instructions from the Create custom Skins Assembly