osTicket software by enhancesoft is the best open-source support ticket system out there. While it is excellent in its function, it packs a very generic design style, and does not come with a responsive layout and UI.
At themedost.com I try to address that issue by making custom themes for the "Front End" of the osTicket software. The themes come with modern design styles and they are responsive and mobile friendly. Unlike the generic version of osTicket, these templates gives a unique identity to your website and provide your customers a smooth interactive experience.