Created attachment 172175 [details]
Somewhat reduced HTML
Extra space (not sure if it's padding / margin or a void) is appearing around some elements, possibly just a table.
Created attachment 172176 [details]
Created attachment 172177 [details]
Found the offending revision, and it has been rolled out already. This issue should be resolved in the most recent nightly.
*** This bug has been marked as a duplicate of bug 101198 ***
Confirmed, fixed in latest nightly.