The aim of these versions was to improve the HTML export.
The SrcSet tag is still on no browser, so it is very tough to export images for many resolutions. One should be aware that tablets and even screens now have pixel densities bigger than 1x. I.e., one image pixel might be many screen pixels. For 300 dpi, graphics would be far too small otherwise. To adjust for this, Euler can link to 3x images, which are used to anti-alias the image anyway. This looks great in Chrome, especially on tablets. But others browsers have still horrible algorithms to downscale images. Shame on Firefox.
By default, Euler is now using paragraphs instead of preformatted text. This does not look exactly as in the notebook, but I like it much more. Moreover some markdown is possible, such as lists with a simple „-“ tag. I might expand these options in the future, and also apply the formats to the PDF export.