Manager is not a what-you-see-is-what-you-get application. It functions as a browser. So when you view something onscreen, it renders according to HTML coding and will display most things, including font attributes and formatting. But when you generate a PDF, it uses an internal PDF generator to create a file. The first thing to understand is that everything is converted to Google’s Noto font. And formatting options become more limited. That is necessary to handle all the various spacing and font issues that can arise with the 70 languages Manager is translated into.
The second thing to know is that the depiction of themes only shows a generally representative view. No particular transaction form is displayed. So no invoice, sales quote, inventory transfer, or other transaction form will look exactly like the sample.
The third thing is that, while screen views are rendering HTML, themes are written in Liquid. Liquid is similar in many respects to HTML, but not identical. Your subject for this topic refers to the default theme. But I’m fairly certain what you’ve displayed is not the built-in, Plain, theme. You appear to have substituted a serif-style font and converted to landscape document orientation. The PDF generator will not support either.