Zebra is a responsive theme for Moodle developed by Danny Wahl, according to it’s entry it’s
mobile-first, responsive theme that uses CSS3 to reflow the layout for the best experience on every device.
This theme has loads of customization options to change colors, logos and more from the administration settings allowing you to tailor it to your organization’s needs easily. Try it out at http://moodle.iyware.com/
Download it at https://moodle.org/plugins/view.php?plugin=theme_zebra