CHM Output different to editor

[SimonBunyard]

For some reason my CHM output is significantly different to my editor. Even the preview in the editor is different (same as CHM though) and I can't seem to see why.

Here is how my lists look in the editor. The indentation is good, there is a perfect hanging indent on items that go to two lines...

Correct indent.png

But when I preview this in the editor or output to a CHM, my indentations are off...

Incorrect indent.png

Here is my stylesheet...

HTA.css

If anyone can help, I'd appreciate it massively. Thanks