The new Kempelton version has an updated back and forward button style just like Qute 4.1, as well as a few more improvements. Each of the default set of toolbar icons has been carefully tweaked in color and shape. The back and forward buttons are slightly lighter and the stop icon is more subdued and shaded more consistent with the other icons.
With such a simple design as that of the Kempelton reload icon, you might think it would be easy to find the right shape, but I have kept finding the need to refine it in pretty much every version.
Together, I think, the impression is lighter and more balanced and harmonic.
Kempelton Large is also updated.
Icon set additions
The SVG set is updated as well and has a few additions not in the Firefox theme, seen here. They were for an updated Thunderbird theme, but then I lost interest and got less time.