Header Resizing Custom Logo

I am editing the new Twenty Eleven theme to fit my site more (in a child theme of course), and I have put a logo to replace the standard site text. It is a 326px by 90px logo and for some reason, it is being resized to 578px by 160px.

The html code I’m using:
<h1 id="site-title"><span><a href="<?php echo esc_url( home_url( '/' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>"><img src="<?php echo esc_url( home_url( '/' ) ); ?>/wp-content/themes/twentyeleven-child/images/gscd-logo.png" alt="GSC Designs" width="326" height="90"></a></span></h1>

Can anyone help?