Responsive web design is about a lot more than the size of your screen. Kyle Neath, Director of Design for GitHub, talks about about how GitHub handles links, the url bar, partial page updates, and explains why he thinks the HTML5 history API is the most important thing to happen to front end development since Firebug.
No.
$ irb -r set
1.9.3p125 :001 > set = ObjectSpace.each_object(Set).to_set
=> #<Set: {#<Set: {...}>}>
1.9.3p125 :002 > set.include?(set)
=> false
However, the Enumeration of all Enumerations does contain itself.
1.9.3p125 :001 > e = ObjectSpace.each_object(Enumerator) => #<Enumerator: ObjectSpace:each_object(Enumerator)> 1.9.3p125 :002 > e.include?(e) => true
Why this is so is left as an exercise to the reader.
Kyle Neath talks about responsive web design.