Re: PIE and YAML framework
I use PIE with YAML framework and had the same problem with border-radius within (sub)columns, border and bg-color didn't show.
Setting position:relative; on my classes helped for me. Haven't really investigated the YAML ccs code.
Depending on your situation one of these could help:
1. make the target element position:relative, or
2. make the ancestor element position:relative and give it a z-index.