Sub-Nav of child pages in Radiant

sub-nav.html

## In layout
<div id="subnav">
  <ul>
    <r:snippet name="sub-nav" />
  </ul>
</div>

## In snippet named "sub-nav"
## This also adds an "active" class to the current page link
<r:if_parent>
  <r:parent>
    <r:snippet name="sub-nav" />
  </r:parent>
</r:if_parent>
<r:unless_parent>
  <r:children:each>
    <r:if_ancestor_or_self>
      <r:children:each>
        <r:if_ancestor_or_self>
          <li id="<r:slug/>" class="active"><r:link /></li>
        </r:if_ancestor_or_self>
        <r:unless_ancestor_or_self>
          <li id="<r:slug/>"><r:link /></li>
        </r:unless_ancestor_or_self>
      </r:children:each>
  </r:if_ancestor_or_self>
  </r:children:each>
</r:unless_parent>