Where is the air inlet on a Mac mini (2018) for the cooling fan?

On the Mac mini (2018) , where is the air inlet for cooling the innards of this computer? I have looked at the iFixit teardown . It shows the fan blowing out the broad outlet across the back of the Mac mini, below the USB-C ports. I certainly can feel the warm air exiting this outlet. ➥ Where does the air *enter* the Mac mini? The bottom is either solid metal or covered by the non-slip rubber. I see no other inlets on the backside. So I am left puzzled. I am concerned about not blocking the air inlet, to maximize cooling efficiency.