If you open a graph, zoom out with ctrl+minus or the magnifying glass then reload the page once you zoom in even once the quality is reduced & it continues being reduced the more you zoom in. The bug is applies to most* things on the graph but not anything on the left. It is easily fixed by reloading the page again. *The exceptions to this are point labels & oddly the point that appears at the cursor when you hold click on equations, but not the gray points that appear at roots, intersects & extremums unless those are specifically selected.