Using the Chart.bundle.js script (documentation [here](http://www.chartjs.org)), I've created a Line Chart within a object in javascript. Furthermore, my x-axis is numerical, ranging from -100 to 100. It is very important to me that there be a clear distinction between negative and positive numbers, and so I am trying to show a clear, bold x-axis on my Chart object; however, it doesn't seem like Chart.js provides this feature-or perhaps I just cannot find it. Is there any way of making a thicker x-axis? I am open to both conventional solutions as well as hacky ones, if necessary.