If you add .macbook {zoom:4;} you can see how the detail is done. Basically you use lots of box-shadows to give you elements to glue together. The details on the front are not actually solid lines, but a collection of circles side by side.

That's when you realise this technique is a bit flawed - you can't actually scale the element and keep the detail, you'd be better off with an image. Not to take anything away from it though. It's good work.