   scroll: ->
     scrollTop = @$window.scrollTop()
     windowHeight = @$window.innerHeight()
+    PADDING_TOP = 46
     @sections.forEach (section) ->
       top = section.$section.offset().top
       height = section.$heading.height()
       position = 0
-      if scrollTop > top - (section.top)
+      if scrollTop > top - (section.top) - PADDING_TOP
         position = -1
       if scrollTop + windowHeight < top + height + section.bottom
         position = 1

    ).join ' '
$ ->
  application = new Application
  # taxon の読み込み
  d3.json 'taxonomy.json', (data) ->
    application.initialize data

          when -1
            section.$section.addClass('sticked').removeClass 'bottom'
            section.$heading.css
              top: section.top + PADDING_TOP
              bottom: ''
          when 0
            section.$section.removeClass('sticked').addClass 'bottom'
