The base Web controls class offers only a limited number of properties. You can use Cascading Style Sheets (CSS) with Web controls to apply a large variety of formatting styles to Web pages. You can use CSS attributes with Web controls in the same way as with HTML tags.
The simplest way to use CSS is to apply CSS attributes to the Style property of a Web control.
<asp:Label id="lblMsg" runat="server" Style="font:18pt Script" text="This is a Label" />