How to reduce the height of header

hi,
I am trying to reduce the height of the header on our website (www.introtel.com)

header.php code is:

<div id=”header-wrapper” data-size=”big”>
<div class=”container”>
<div class=”row”>
<div class=”top-info-wrapper”>
<!– Logo
======================================================================== –>
<div class=”span3″>
<div id=”logo” class=”pull-left”>
“>
<?php
if(trim($velvet_data[‘logo_upload’]) != ”){
echo ‘<div class=”logo-wrapper” style=”width:’.$velvet_data[‘logo_width’].’px; top: ‘.$velvet_data[‘logo_top’].’px; left:’.$velvet_data[‘logo_left’].’px;”><img src=”‘.$velvet_data[‘logo_upload’].'” alt=”‘.get_bloginfo( ‘name’ ).'” /></div>’;
}else{
?>

‘<div class=”logo-wrapper”><img src=”<?php echo get_template_directory_uri() ?>/images/logo.png” alt=”Velvet” title=”Velvet”></div>
<?php } ?>

</div>
<div id=”showLeftPush” class=”btn-collapse”>
<i class=”fa fa-list-ul”></i>
</div>
</div>
<!– Logo / End –>

where do i change the code t reduce the height