Everything with default settings, except the graph title text, X-axis orientation.
Even though this graph looks fine in my/your browser, the horizontal width
per x-value can easily be of unequal size if the (base) font size set in your
browser is fairly large compared to the pixel size on screen. This is of course
most likely to happen on high resolution screens, but could also be due to
unexpected setttings of the font size in browser preferences/properties.