Microsoft SharePoint 2007 Technologies

14.5 Themes 411

Chapter 14

You can also reference your custom style sheet from your master page by

using the SharePoint

CssRegistration control. In a master page, Share-

Point calls core.css using the SharePoint

CssLink control. Any references to

custom style sheets should appear after this tag. Using the

CssRegistration

control has its drawbacks, namely the fact that the control does not actually

guarantee the order in which the specified style sheet is loaded. This is not

really a problem if your custom style sheet references styles that do not exist

in core.css, but if you are using your custom style sheet to override the styles

in core.css, you should look to using another method such as setting the

alternate CSS URL property. Alternatively, you can use a standard ASP.NET

link control to reference your custom style sheet directly from your master

page. If you place the

link control after the SharePoint CssLink control,

your custom styles will be loaded after core.css. Figure 14.28 shows the

HTML for referencing a custom style sheet using both the

CssRegistra-

tion

control and the ASP.NET link control. The drawback of using the

link control method relative to the alternate CSS URL method is that the

style sheet only affects pages that inherit the master page containing the refer-

ence. As we mentioned earlier in the chapter, the majority of the pages in

the _layouts directory are controlled by the application.master, which means

that the application.master would have to include the

link control.

Microsoft does not support the modification of system pages such as applica-

tion.master. From a best practice standpoint, you should try to perform as

much customization as possible through the use of custom style sheets and

then leverage the alternate CSS URL setting to achieving a consistent look

and feel with respect to style settings throughout your site collection.

It is important to note that, as with master page settings, new sites do

not inherit the alternate CSS URL setting from the parent. As with master

pages there are several techniques to choose from should you want newly cre-

ated sites to reference a specific alternate CSS file upon site creation. These

techniques are discussed in Chapter 15, Site Definitions nad Templates and

Chapter 16, Features.

14.5 Themes

Designing a Web page so that it is both visually appealing and effective is of

paramount importance to the ultimate success of the site. Not all Web sites

are created by professional Web designers who know all of the intricacies and

Figure 14.28

SharePoint:

CssRegistration and

ASP link tags.