       unhovers.onValue '.classed', 'hovered', false
 
       if type is 'line'
-        area_opacity = params.areaAlpha ? 1.0
+        area_opacity = params.areaAlpha
         line_opacity = 1.0
 
         area = d3.svg.area()

            'line'

        stack = d3.layout.stack()
          .offset(params.areaOffset ? 'zero')
          .values((d) -> d.values)
          .x((d) -> d.time)
          .y((d) -> d.value)

      legend_target.append('span')
          .text((d) -> d.name)

      svg.style 'background-color', params.bgcolor

