[Theme: Twenty Twelve] Header is broken when width size is 602px below

We were maintaining a website that was handed to us and we accidentally remove the media queries in styles.css and now the website is not responsive(header part). We have done some editing to restore its responsiveness but it won’t work when the size is reduced to 602px and below. We also copied the original media queries in twenty twelve theme. We add a slider (Cyclone slider). We did not use a child theme so there is no back up. [lesson learned]
This is the site
http://mirzadesigns.com/
and this is the result when minimized to 602px.
http://www.viewlike.us/operator/#u=http://mirzadesigns.com/|602|957.76666

Thank You