title: how to write spec for responsive website?
body: <p>I'm about to write spec to responsive website that has web, tablet and mobile versions.
  this is the first spec I'm writing to responsive site, and I'm not sure which format would be the best understood:
  - Should I write different spec for each version (PC, Tablet and Mobile)?
  - Should I write everything in one ducument and describe the differences in each version?
  - Are there any further things you think it's important to take in mind when writing this kind of ducument?
  any examples or tips will be welcomed, thanx!</p>