Customize Category Content

<?php
/**
* Category Page Template.
*
* @package Impressive
* @author Adam Abrams <adamabrams@shaw.ca>
*/

//Add Post Class Filter
add_filter('post_class', 'sf_post_class');

function sf_post_class($classes) {
    global $wp_query;
    $classes[] = 'one-third';
    if( 0 == $wp_query->current_post || 0 == $wp_query->current_post % 3 )
     $classes[] = 'first';
    return $classes;
}


remove_action('genesis_loop','genesis_do_loop');
add_action('genesis_loop','custom_loop');


function custom_loop() {
while(have_posts()) : the_post();
    echo '<div class="loopthumbnail">'. the_post_thumbnail('thumbnail') .'</div>';
    echo '<div class="loopdate">'. the_date() .'</div>';echo '<div class="looptitel"><a href="'.get_permalink().'">'.get_the_title().'</a></div>';
endwhile;
}

genesis();