[Papi]

I currently have the PRS 950, 650 and 350. And looking closely, displaying a book with the same font, it seems to me the bigger the screen, the lesser contrast it has. Actually the difference between the 950 and 650 is bigger than the one between 650 and 350. The latter could be explained by the difference in DPI which is greater on the 350, making the text look sharper and overall easier to the eye.
The 650 casing is black while the 950 casing is gray. The darker the case, the whiter the background seems, but it seems to me there is more to it. So my question is pretty simple : has anyone the 950 and another of the PRS series to confirm / infirm the difference in contrast ?

I have another question : I installed boroda's firmware and PRS+, and using the same userStyle.css, the presentation of the text is not exactly the same between the 950 and 650, despite their screens having the same width. See the picture below : the beginning paragraph on the 650 has on more word compared to the same paragraph on the 950. Anyone has any idea why ?