Twenty-Eleven theme stretching my logo image

Looking to adjust the size of my logo on my site to the nominal size that the image already currently is at 476×83

I know this has been asked before but none of the solutions worked for me.

My site located at divesummit.com is stretching this logo image.

I tinkered with the style.css a little but still can’t get it to be the nominal size of 476×83

I currently have this code in the functions.php portion of the child theme:

<?php
define( ‘HEADER_IMAGE_WIDTH’, apply_filters( ‘twentyeleven_header_image_width’, 487) );
define( ‘HEADER_IMAGE_HEIGHT’, apply_filters( ‘twentyeleven_header_image_height’, 183 ) );
add_filter( ‘woocommerce_page_title’, ‘woo_shop_page_title’);

function woo_shop_page_title( $page_title ) {

if( ‘shop’ == $page_title) {
return “My new title”;
}
}
?>

What must I change/adjust to have the image load at the above mentioning size.

Thanks so much for all your help and all the help the www.ads-software.com forum community offers to everyone.