Make the title header and logo bigger

Hi all,

My webpage is clmresolution.co.uk and as you will be able to see I have a header bar with an image.

I would like to make the image bigger using custom css.

I have edited the style.css file by adding

/* Masthead - Shrink to scroll */

header.shrink {
height:50px;
transition: all 0.5s ease-in-out;
-moz-transition: all 0.5s ease-in-out;
-webkit-transition: all 0.5s ease-in-out;
-o-transition: all 0.5s ease-in-out;
}

and also edited the functions.php with

/*Make header shrink on scroll */

add_action ('wp_footer', 'vr_shrink_head',1);
function vr_shrink_head() {
?>

<script>
jQuery(document).ready(function($) {
$(window).scroll(function () {
if ($(window).scrolltop()>100 {
$ ('header').addclass('shrink');
}
else{
$('header').removeclass('shrink');
}
});
});
</script>
<?php
}

how would I go about increasing the size of this image but it still shrinking with the code that I have added.

many thanks

adam