By default KLEO generates the images at the size of 460x270 for your archive pages like your main blog page or category page. To change the image dimensions you just need to have you child theme active and add this small snippet to kleo-child/functions.php
COPY CODE
add_action( 'after_setup_theme', 'kleo_custom_media_size', 20 );
function kleo_custom_media_size() {
global $kleo_config;
$kleo_config['post_gallery_img_width'] = 260; //initial was 480
$kleo_config['post_gallery_img_height'] = 146; //initial was 270
}
