The PRS-700 uses a very very old version of mobile ADE that does not support justified text. All recent versions (or even just very old versions) do support this. The PRS-950 does support text justification. I'm not sure if it is the default, but if an ePub asks for justified text that is what you get.
There are two ways to fix this: a) for DRM-free ePubs use Calibre to change the text alignment (to left) one ebook at a time, or b) change the default for all ePubs on your PRS-950.
I am not an expert on the PRS-950, but it is my understanding that you need a modified firmware to allow a user-provided userStyle.css (to over-ride justification). See
SONY PRS950 for Chinese - problem with book title. You don't care about fonts, but this allows a userStyle.css.
What I use for calibre extra-css or as userStyle.css:
Code:
body {
font-family: sans-serif;
font-weight: bold;
text-align: left;
}
You don't need to use the font-family or font-weight defaults unless you like sans-serif (default is serif) or an always bold font. Just delete the lines you don't want.