If you plan to use the same web site for your PC and mobile device you should use two different style sheets (CSS) or look and feel for the two different delivery options.
Style sheet support is not standard or current on mobile devices.
There are many considerations to make when you create a web site's look and feel, also referred to as branding, for mobile delivery.
Branding over a mobile devices is very bare bones. You do not have the screen real estate for big fancy graphics.
It's True! This course is available to be viewed from a PC and a Mobile. The look and feel is different depending on the device you are using.