We don't keep any border style properties or some individual background/font properties around to keep the cache smaller, as you can access the border property itself. I don't plan on changing this currently, as there are usually ways around it using the "complex" properties. What are you trying to do?
I figured out that I can use it just as @property.border but it also prints border: and border-radius: that I don't really need.
For example I want to set a custom padding like: padding-left: @property.padding and I won't be able to do it because it prints the complete rule, which differs from .padding-left for example, that outputs only the value itself.