One of my coworkers built this code, but I've been trying to troubleshoot for about an hour and a half. The sidebar has lots of extra spacing in most Outlook versions (it gets hidden in mobile) so I've tried everything - making it fixed height and width, etc. to no avail.

https://litmus.com/pub/5fb5034/screenshots

Here is the scope so you can see the code. Unfortunately it scoped the first version without images added, but that doesn't make too much difference: https://litmus.com/scope/5adgmr7h55oh