The Portal UI is composed of several different blocks, as described in the following screenshot:
If you have ever worked with SharePoint, you will see some familiar stuff. One thing to remember though is that the FIM Portal is not just another SharePoint site; you will realize this as soon as you start to look at, for example, the forms we use in FIM.
But many of the graphical changes we can make are the same as in SharePoint.
In the upper-right corner, we will find some familiar menus if we have worked with SharePoint.
If we go into Site Settings and click on the Site Theme option, we will see that FIM installed its own SharePoint theme called FIM, which is used by the FIM Portal site.
If you are thinking about trying to use another theme or trying to use this theme on other sites, forget it. I have made some tries in a few customer cases but have always realized the theme is quite specialized to use with the FIM Portal.