I don't think it has anything to do with Apple (although I certainly could be wrong as I only have Windows and Android to check it on). I think it is strictly a matter of the pixel width being used to display the page.
Images below reduced in size 25%:
Here is your message on a normal desktop window on Windows:
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As the window width is reduced, at some point the forum software accommodates the narrower window by dropping the blue side bars and the left poster information column, and changing the message format to this:
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In the narrower format, some information is rearranged, but others are dropped.
Further reductions in window width change the line-wrapping length, but no further layout changes until you reach the point where it won't shorten the text lines any further and you'd have to scroll left/right to see the entire message:
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