Hurray, I finally fixed another rendering bug in tt that was bugging me for a long time. Previously, when there were empty lines in a markdown multiline code block, the background color of the code block had not been used for the empty lines. So, this then looked as if there were actually several code blocks instead of a single one.

https://lyse.isobeef.org/tmp/tt-bugfix-empty-lines-in-multiline-code-blocks.png