all sub items inherit &hereClass

[[!Wayfinder?
  &startId=`2`
 &outerTpl=`subnav-menuOuter`
  &rowTpl=`subnav-menuRow`

  &hereClass=`current`

   ]]

<!-- rowTpl -->
<li[[+wf.id]][[+wf.classes]]>
<a href="[[+wf.link]]" title="[[+wf.title]]" [[+wf.attributes]]>[[+wf.linktext]]</a>
[[+wf.wrapper]]
</li>

#sidebarSubnav .current a {
    color: #1D74B3;
}

<!-- rowTpl -->
<li[[+wf.id]][[+wf.classes]]>
<a href="[[+wf.link]]" title="[[+wf.title]]" [[+wf.attributes]][[+wf.classes]]>[[+wf.linktext]]</a>
[[+wf.wrapper]]
</li>

#sidebarSubnav a.current {
    color: #1D74B3;
}