Thanks, I downloaded the plugins for calibre, enabled the fullscreenreading and insered the .css file to correct the margins and now the ereader works wonderfully!
But I was thinking: with this tweaks am I risking to brick or do harm to the device?
If they are safe, could you copy a link with others interesting features that I can enable with the Notepad++ ? (I searched but I haven't found a complete list
)