Kiandra has recently announced the open sourcing of Delta jQuery UI theme that you’re going to love. It’s free for commercial, personal and educational use as part of the MIT or GPL license.
The theme makes use of CSS3 gradients and some @2x images to ensure it’s retina display friendly. The vibrant colour scheme means “Delta” works on both light and dark backgrounds. Change the toggle in the top right hand corner of the demo to see it in action.
This theme can act as a starting point for other smart cookies to create their own visually engaging jQuery UI themes. You can fork this theme over on the GitHub repository.
Requirements: jQuery UI
License: MIT, GPL License