They'll probably mention it as-designed however if you take a look at node_list.css, you'll notice it pulls from two different sources:
Code:
.nodeList .categoryStrip
{
@property "subHeading";
font-size: 11px;
color: @secondaryDarker;
background: @secondaryLighter url('@imagePath/xenforo/gradients/category-23px-light.png') repeat-x top;
padding: 5px 10px;
margin: 3px auto 0;
border-top: 1px solid @secondaryLighter;
border-bottom: 1px solid @secondaryLight;
@property "/subHeading";
@property "categoryStrip";
padding: 5px 10px;
margin: 0;
border-bottom-color: @subHeading.border-bottom-color;
border-radius: 5px;
min-height: 6px;
@property "/categoryStrip";
}
And also:
Code:
.nodeList .categoryStrip .nodeTitle
{
@property "categoryStripTitle";
font-size: 10pt;
color: @secondaryDarker;
@property "/categoryStripTitle";
}
Go to Style Properties -> Forum / Node List -> Category strip Title
So while your subheading will effect your category strips to an extent, settings in the Category Strip + Category Strip title will potentially override those settings.