If an element does not have a border the innerWidth and innerHeight functions of the dimensions plugin cause a NaN result. It is a very simple fix. Just need to add || 0 to each of the parseInt calls on line 81 and 99.

Line 81:

this.get(0).offsetHeight - parseInt(this.css("borderTop")) - parseInt(this.css("borderBottom"));

Should now be

this.get(0).offsetHeight - parseInt(this.css("borderTop") || 0) - parseInt(this.css("borderBottom") || 0);

Line 99:

this.get(0).offsetWidth - parseInt(this.css("borderLeft")) - parseInt(this.css("borderRight"));

Should now be

this.get(0).offsetWidth - parseInt(this.css("borderLeft") || 0) - parseInt(this.css("borderRight") || 0);