If you are having issues with Master pages and page layouts, please also see this article.
This affects the following elements:
- Master Pages
- CSS (style, formatting, etc)
- Color palettes
- Font palettes
- Background images
If the options exist in the destination version of your migration, you can manually create a site with the same look and feel, and copy the source site into it (to merge the content with the theme).
You can use SharePoint Designer for the color palette (as long as it is a compatible version). To do this, you need to navigate to the following in SharePoint Designer:
- Your site
You should now see your file(s) after navigating to that location.
You can now copy those file(s) to the same spot in your destination site.