Dear friend
I am Joomla Developer.I have worked and had much deeply experience in Joomla Responsive template + virtuemart .If you want to ensure, please check my reviews on related jobs in my profile.
About your project, I can fix these messy css code, [ both checkout page, product page, order page in email template...]
I guarantee
+ Clean code, native responsive layout, works well with all mobile and tablet device
+ Full document and guide after moving it to production site
+ Have warranty you at least in 1 month if have any problem
+ Good in English and ensure to reply you within 1 or max 2 hours
I really want to work with you on this project so looking forward to starting now. Thank you for your attention
Developer
Linh