LJ Styles

I'm so vexed. My LJ style, based on Flexible Square, broke; all replies to posts don't have the correct colour background, and and no longer indented. I can't remember what I did when I set the style up years ago, so I don't even know where to start. I'm not sure I feel like spending hours trawling through CSS code. In the meantime, I've reverted to the previous style I used, which OK, but missing many customisations.

Grr.