The Now Playing panel appearance is different in the original and mobile versions and will depend on what’s playing
Most of this is self explanatory.
Cover Art will only display if the album has associated Cover Art. You can choose to display a bigger image by checking the Big Picture box in Settings but that will hide the graph and progress slider and will reduce the size of the panel beneath Now Playing.
If you click on the track, album or artist then one or both of the Artist and Album panels will update to reflect what you clicked on.
The graph shows you when music is playing and is also a useful confirmation that your Wifi connection is OK - the line will break when the connection is interrupted.
The progress slider may be greyed out or inactive for some music sources - like Apple m4a files or internet radio.
The Navigation Bar takes you to the main sections of the mobile Web UI.
Volume is controlled by buttons instead of a slider on the Mobile version
Tapping on details will take you to the Artist or Album panel for that item.
There is no progress slider or tone control on the mobile version.