$ ->
  log = (x) ->
    console.log x

  navs = $('#navs').children()
  divs = $('#divs').children()

  crntPage = 0;

  # @ means 'this'! wow!
  navs.each (index) ->
    $(@).click ->

      diff = index - crntPage

      # ここの処理もっとスマートにしたい
      deg = if diff > 0 then 0 else -180
      range = if diff > 0 then [crntPage..index] else [crntPage...index]

      # 覆う処理とめくる処理とでは、似ている処理のようだけどindexの終端がずれる
      for i in range
        $(divs[i]).css 'transform', "rotateZ(#{deg}deg)"

      crntPage = index