Site themes in SharePoint 2007 were incredibly powerful as they allowed extensive customization of site look-and-feel including the use of custom CSS and images. Rather than simply changing colors by overriding default styles, site themes could really affect not just the aesthetics of a site but also functionality! A site theme could transform SharePoint to something more like Google Music:
In this relatively conservative theme (read: site themes are capable of even greater customization!), the general design was changed and some enhancements (that are not shown in the screenshot) were also implemented. For example, various hyperlinks (e.g. Quick Launch headers and items) are displayed as a block element with 100% width, making them easier to use. However site themes can’t accomplish such a look-and-feel in SharePoint 2010…
Site themes have changed significantly. They are now Office themes and are not specific to SharePoint; therefore, they no longer support custom CSS or images! Site themes are now limited to specifications of color. So, the alternatives might be using a custom masterpage or adding Web Parts to to each page… however such solutions really aren’t too desirable and have significant limitations, especially when working with large sites/site-collections. There is a much simpler (and better) approach if using a site with the SharePoint Server Publishing feature available.
Publishing sites in SharePoint 2010 (and SharePoint 2007, actually) provide the incredibly useful setting to specify a custom URL for alternate CSS. The specified CSS will be loaded after the default SharePoint stylesheets, so it can effectively be used just like old site themes in SharePoint 2007. Additionally, it provides the option to reset all subsites to use the specified custom CSS URL. Using this method, a custom look-and-feel can be applied to all pages with minimal customizations and maintenance overhead.
The following steps may be followed to apply custom CSS and images on a site/site-collection:
- Add custom CSS and images to the site or site-collection
(e.g. in the _layouts virtual directory or a document library on the top-level site) - Enable the SharePoint Server Publishing feature
(Site Settings > Site Actions > Manage site features) - Specify the Alternate CSS URL setting
(Site Settings > Look and Feel > Master page)