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## ASP.NET WebControl CssClass Property The `CssClass` property is a fundamental styling property used in ASP.NET Web Forms. It allows developers to apply CSS (Cascading Style Sheets) classes to server controls, enabling a clean separation of presentation (CSS) from application logic and markup. --- ## Definition and Usage The `CssClass` property gets or sets the CSS class rendered by the Web server control on the client browser. When the ASP.NET engine renders the page into HTML, the value of the `CssClass` property is compiled into the standard HTML `class` attribute of the corresponding HTML element. --- ## Syntax ```xml ``` ### Property Values | Property Value | Description | | :--- | :--- | | `style-class-name` | A string value specifying one or more CSS class names to apply to the control. Multiple classes can be separated by spaces (e.g., `CssClass="btn btn-primary"`). | --- ## Code Example The following example demonstrates how to define a CSS class in a `

``` ### Rendered HTML Output When the page is requested by a browser, ASP.NET renders the server control as standard HTML: ```html ``` --- ## Key Considerations ### 1. Applying Multiple Classes You can apply multiple CSS classes to a single control by separating the class names with a space, just as you would in standard HTML: ```xml ``` ### 2. Programmatic Manipulation You can dynamically get or set the `CssClass` property in your code-behind file (C# or VB.NET) during page lifecycle events (such as `Page_Load`): **C#:** ```csharp protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { Button1.CssClass = "TestStyle"; } } ``` **VB.NET:** ```vb Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load If Not IsPostBack Then Button1.CssClass = "TestStyle" End If End Sub ``` ### 3. CssClass vs. Inline Styles While you can use individual style properties (like `ForeColor`, `BackColor`, `Font-Bold`) directly on an ASP.NET control, using `CssClass` is highly recommended for production environments. It keeps your markup clean, reduces page weight, and ensures consistency across your web application.