Why do checkmarks appear in different colors?

[Accessibility UTA]

In Adobe Acrobat Pro, the checkmarks in check boxes appear black.  If the same file is opened in a browser (Sharepoint or Teams), the checkmarks appear as orange - which fails the minimum color contrast required by WCAG 2.1 AA.

How do I force the checkmarks to always appear as black, no matter how the document is viewed?

[MikelKlink]

PDF viewers, when showing form fields, can display them using a custom appearance. This custom appearance actually is not defined by the PDF specification but really custom, it is based on some hints in the PDF but not fully defined by them. Furthermore, PDF files can contain a complete appearance for each form field which the PDF viewers can also use.

What you observe, therefore, is a situation in which the appearances the different PDF viewers show differ greatly.

If you are lucky, the orange checkmark appearance is the appearance (or derived from appearance hints) from inside your PDF because in this case you can update your PDF to contain a good appearance (or good appearance hints).

If on the other hand it's the custom appearance generated by the viewer, it is not under your control but may depend on the viewer configuration.

Ah, if your files contain hybrid form definitions (AcroForm and XFA), that's another possible cause for your observation. Some viewers then display the form as described using AcroForm objects while others display it using the XFA XML data. And these form definitions may differ considerably.

As you did share an example PDF to illustrate the issue, I can just name some possible causes but I cannot tell you which it is in your case.

[Thom Parker]

I think what Mike means to say is that it should not happen. The appearance of those checks is explicitly defined in the PDF, which is what PDF is all about. By definition, a PDF file should look exactly the same in all viewers on all platforms.

If it is not displayed the same, then that viewer is non-compliant piece of crap and you should avoid using it.