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Cascading Style Sheets in .NET. Lilian Kiilu, Client/Server & Web Applications, Coms 463/563, Section 1pm, Fall 2005, November 16 th 2005. Cascading Style Sheets in .NET. CSS separates content from design in Web Forms applications.
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Cascading Style Sheets in .NET Lilian Kiilu, Client/Server & Web Applications, Coms 463/563, Section 1pm, Fall 2005, November 16th 2005
Cascading Style Sheets in .NET • CSS separates content from design in Web Forms applications. • Maintains and consolidates visual aspects of Web development. • Reduces structure code and increases manageability. • Design elements such as visual layout, color and positioning to a style sheet. • Eg Instead of : • <td bgcolor=“Blue”> use <td> • In the style sheet define <td> as a blue. • Any changes to be made across all <td> tags can be made just once in the style sheet. • Cascading style sheets work in terms of inheritance. Correct order to apply styles to elements on a page: • Included files (external files) • Head items (within the <style> tag) • Inline styles
Included files • Used to refer to external style • Put in the <head> tag • Using <link> tag <head> <link rel="stylesheet" type="text/css" href="mystyle.css" /> </head> • Ideal when the style applies to multiple pages • Example style sheet: Hr {color: sienna} p {margin-left: 20px} body {background-image: url("images/back40.gif")}
Head Items • Used when a single document has a unique style. • Style definition in the <style> tag within the <title> tag <head> <style> h1 { color:black } </style> </head> • An old browser may ignore unknown tags eg the <style> tags
Inline Styles • Mixes content with presentation • Style definitions applied directly to an element using the style attribute. <h1 style = “color:black;”> Welcome </h1> • Styles are applied either by setting the style or the class attributes. Example: how to change the color and the left margin of a paragraph: <p style="color: sienna; margin-left: 20px"> This is a paragraph </p>
Multiple style sheets • If one selector is defined in different style sheets, the values will be inherited from the more specific style sheet. Example:1. External style sheet: h3 { color: red; text-align: left; font-size: 8pt } 2. Internal style sheet: h3 { text-align: right; font-size: 20pt } • If the page with the internal style sheet also links to the external style sheet the properties for h3 will be: color: red; text-align: right; font-size: 20pt
Background color properties • background-color: • Sets the background color of an element • color-rgb • color-hex • color • transparent • background-image: • Sets an image as the background • url • none • background-repeat: • Sets if/how a background image will be repeated • repeatrepeat-xrepeat-yno-repeat • background-attachment: • a background image is fixed or scrollswith the rest of the page • background-position: • Sets the starting position of a background image • top left • top center • top right • center left • center center • center right • bottom left • bottom center • bottom right • x-% y-% • x-pos y-pos
Text properties • Color : • Sets the color of a text • color • Direction: • Sets the text direction • Ltr • Rtl • Text-align: • Aligns the text in an element • Left • Right • Center • Justify
Setting style attributes • Standard HTML tags • All ASP.NET Html tags style like standard HTML tags • Styles are passed along to the browser • Source Code • View Browser
Setting Class attributes • Makes it easier to define styles once. • Changes made to class attribute without having to redefine the style itself. • Source Code • View Browser
Applying styles to web server controls • The System.Web.UI.WebControls namespace includes a Style base class that encapsulates common style attributes. • Advantages: • Provide compile time checking • Statement completion in .NET • Example show how a WebCalender control looks with several styles applied to it : • Source Code
Programmatically setting controls • Using the ApplyStyle method of the base WebControl class: <script language="VB" runat="server"> Sub Page_Load(Src As Object, E As EventArgs) Dim MyStyle As New Style MyStyle.BorderColor = Color.Black MyStyle.BorderStyle = BorderStyle.Dashed MyStyle.BorderWidth = New Unit(1) MyLogin.ApplyStyle (MyStyle) MyPassword.ApplyStyle (MyStyle) MySubmit.ApplyStyle (MyStyle) End Sub </script> Login: <ASP:TextBox id="MyLogin" runat="server" />/<p/> Password: <ASP:TextBox id="MyPassword" TextMode="Password“ runat="server"/> View: <ASP:DropDownList id="MySelect" runat="server"> ... </ASP:DropDownList> Source Code View Source