I am trying to get a line graph to display correctly on my site, but for some reason it wants to overflow the graph container. I have tried reset the box-sizing to initial,
This might be happening if you are using <base href>
directive on your web page. In those cases references to masking filters in SVG do not work properly, hence lines protruding from plot area.
To avoid that simply add the global baseHref setting line to your code:
AmCharts.baseHref = true;
Please note that this must be a standalone line (not a part of chart config) and go before any of the code that creates charts.