div containing graph gets continually smaller

[lo-co]

When stretching the window from left to right and vice versa, the graph gets continually smaller until it the height of the div containing the graph goes to the height of the legend plus a margin.

[lo-co]

This seems to be because the parent of the graph element has no height associated with it, so that when the height is recalculated on a resize, it is always decreasing. This does not seem to happen when you stretch the window top to bottom?