Ruby Case Conditional with AND operator

I wrote a simple, ugly nested conditional to achieve the following:

To achieve the following:

Return "true" if the year meets the following conditions:

1. Is divisible by four
2. AND is not a century year (e.g.) 1900
3. UNLESS it is divisible by 400 (e.g. 400, 800, 2000)

I wrote an ugly nested conditional:

if year % 4 == 0
  puts "Divisible by four"
  if year % 100 == 0
    puts "Century year"
    if year % 400 == 0
      puts "Quad-century year, leap year"
      true
    else
      "Not a Quad-century year, not a leap year"
      false
    end
  else
    puts "Not a century year, leap year"
    true
  end
else
  puts "Not divisible by four: not a leap year."
  false
end

I tried to achieve the same with a case conditional, but it fails to detect the number 2016 as leap year:

case year
when (year % 4 == 0 && year % 100 != 0)
  true
when year % 400
  true
when year % 4 != 0
  false
end

Two questions:

1. What am I doing wrong in my case conditional?
2. Is there a better way to achieve this?