It counts a space after Στερεό as a mistake... Instead it wants a comma directly after, and without a space start with υγρό. That seems like a mistake :)
Remember the days of the "cats whiskers" subsequently the solid state radio or "stereo"?
Learn something every day. I thought it referred only to sound or vision. stereo- a combining form borrowed from Greek, where it meant “solid”, used with reference to hardness, solidity, three-dimensionality in the formation of compound words: stereochemistry; stereogram; stereoscope.