Hi!
Long-ish timer user, first time bug-reporter. I'm using 3.0.14 so maybe this is already fixed, in which case you can disregard.
I was writing a description that involved a string that had extra spaces in the middle. I figured reviewboard would eat the extra spaces by default so I decided to enable markdown and wrap it in a `code` block... the spaces got eaten anyway!
Looking at the CSS it looks like the code blocks are supposed to have `white-space: pre`, but it gets overridden by another selector? I'm not a web developer so I don't really know what this means or how to fix it but I hope this helps!
Picture attached to demonstrate the bug and my findings.