Originally Posted by holdit
I have a Kindle Fixed Layout template ( just the .mobi file ) My goal here is to unpack the file add and change some images and convert the content.opf into a new mobi. The only way I thought I could do was to open the .mobi in Calibre convert the .mobi to an epub , unzip that , make the changes and save as a new .mobi.
When I did this I lost the fixed layout dimensions so I'm asking is there another way to do this?
Yes, a mobi file is not a fixed layout file, no way, no how. It is only used in the KF8 format. If you don't know the difference see our wiki. You can unpack your current file and make your changes but then use KindleGen or its equivalent the Kindle Previewer to make your changed format in KF8 which is the only format that supports fixed layout. The wiki also have a page on Fixed layout ePub which shows the Amazon fixed layout format.