Not sure why it doesn't recognize the span properly and how to fix the entity issue.
Pretty sure those issues aren't related to the image scaling though.
I think its the use of tables to build the postbit. Look at how the mybb default classic postbit works; no tables apart from the containing table.
Yeh, it's the tables. I didn't even bother to try and change that so just went with another theme.
Thanks for the help.