A lot of work has been done to the theme architecture in the latest versions of WebSphere Portal. One of the nice things built into the theme architecture is being able to change the profile for each Portal page, the profile being made of web resources, such as HTML, CSS and JavaScript files and libraries. This allows you to load only the necessary resources on a page-by-page basis. The profile is made up of one to many modules, the modules containing the various web-based resources (i.e. HTML, CSS, JavaScript). An example of a module would be jQuery, meaning, if the jQuery module is added to a profile, any page that uses a profile containing the jQuery module would pre-load the jQuery resources that make up that module, in turn, allowing any portlets on that page to use the jQuery resource (i.e. libraries) as well. Another example of a module would be the Content Template Catalog (CTC) module, which loads all of the web resources libraries required by CTC.
In a prior blog post (here), I discussed a way to show / hide the Edit Mode link contained within the theme. In v8.5, the Edit Mode link is replaced by the new Site Toolbar (click here to read more about the Site Toolbar). The Site Toolbar is another example of a module that is placed in all of the v8.5 profiles, so to remove the Site Toolbar, it would be as easy as removing the Site Toolbar module from any of the profiles associated with Portal pages in which you don’t want the Site Toolbar to be displayed.
Click here to learn more about Developing Themes for WebSphere Portal v8.5.