This is a quick and simple technique to get anti-aliasing via CSS by rendering at a higher resolution. The renderer method
setSize is altered for this and accepts a third parameter for the scale.
For performance reasons FXAA or one of the other post-effect methods are a better option though for most cases, especially at fullscreen resolution. For smaller outputs such as a page element (product viewer) it might be still relevant regarding quality.
Notice the axis helper appears slightly faded, this is due line-geometries being always rendered with a thickness of one pixel by default.