The author of this article decided to take research at three different widths full width desktop,mid-died and small. One of the studies he did was to find out Serif or Sans-Serif? As to be expected, most sites had a serif typeface as a heading and sans-serif for the body copy. Thankfully Times New Roman was not popular! Of course, reading distance is key when considering what font size to use! The average ration of line height was around 1.5 times the size of the body copy, which is what it should be.