I think that, in general, that's probably the case. I certainly spent a lot of time with Dr. Google and Mr. Stackoverflow looking for alternatives. It may still be the case, however, that an approach does exist that no one has yet figured out.

If it is possible to place constraints on the content that is being inserted, namely:

1. It is all contained in an single parent element (e.g. a `<div>`).
2. That parent element has an explicit width

Then there is an alternative approach that would preserve the `margin: auto` behavior. The current implementation of pdf2htmlEX does happen to generate markup that meets those constraints; however, it would seem risky to assume that pdf2htmlEX will **_always_** meet those constraints (e.g. in later releases). Certainly there is nothing in the pdf2htmlEX code to compel or even imply that this behavior will remain consistent.