I'm successfully using helgatheviking's answer from this post: Show children of top level category only See code below:
// get the category object for the current category
$thisCat = get_category( get_query_var( 'cat' ) );
// if not top-level, track it up the chain to find its ancestor
while ( intval($thisCat->parent) > 0 ) {
$thisCat = get_category ( $thisCat->parent );
}
//by now $thisCat will be the top-level category, proceed as before
$args=array(
'child_of' => $thisCat->term_id,
'hide_empty' => 0,
'orderby' => 'name',
'order' => 'ASC'
);
$categories=get_categories( $args );
foreach( $categories as $category ) {
echo '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . '>' . $category->name.'</a>'; }
?>
However, in this list of sub categories, I need to highlight the current category. I'm sure there is an easy answer, but I can't figure it out myself.