add_action( 'genesis_before_while', 'custom_posts_wrap_open' );
/**
* Add opening div.posts tag for posts.
*/
function custom_posts_wrap_open() {
echo '<div class="posts">';
}
add_action( 'genesis_after_endwhile', 'custom_posts_wrap_close' );
/**
* Add closing div.posts tag for posts.
*/
function custom_posts_wrap_close() {
echo '</div>';
}