I have viewed the demo for custom CSS and found that I can accomplish the following:
1) when using the Metro skin on the Q1 2014 release, when you select a child node the top level node remains with the blue background. This confuses my client because it appears that both are selected. I have changed the indent and other properties, but that does not satisfy them.
2) I changed the ExpandedCssClass value to my custom "noBlue" as shown in the code.
3) This works
4) afterwards I spent an hour trying to generalize the style so that the default "rpExpanded" could be left in the panel definition, but the blue background on the expanded item suppressed. I have no clue
5) I found a sample in an older posting, not specific to my needs, but indicates to me that I need something that starts with ".rp" that references the background color or similar part of the panel control.