Google’s John Mueller said in a Google+ Hangout on Friday morning that you do not need a specific desktop web site, that having a mobile site is perfectly fine. Google will rank and list your mobile web site on the desktop search results just fine. So going mobile first, or mobile-only, works perfectly fine with Google.

John answered the question at the 12:50 mark into the video:

Question:

Answer:

Here is the video embed at the start point:

Forum discussion at Google.