         style("stroke-width", (link) -> link.value()).
         style("stroke", (link, i) -> link.color()).
         style("fill", "none").
-        style("opacity", 0.7).
+        style("opacity", 0.6).
         attr("d", (link) => @link_line link.path_points()).
         on("mouseover", @link_mouseover).
         on("mouseout", @node_mouseout)

    # this method is called when we first render the chart. It is called if we
    # want a full chart refresh when the user resizes the browser window, too
    draw: =>
      @margin = 50
      @width = (@container_node().width()   || 490) - 2 * @margin
      @height = (@container_node().height() || 402) - 2 * @margin

      # set up the scaling methods
      @x = d3.scale.linear().domain([0, 600]).range([0, @width])

  # cool but not flexible enough
  Node: class extends Backbone.Model
    @width: 100
    @horizontal_spacing: 250
    vertical_margin: 10

    initialize: =>
