Cobalt used to free but we were getting "demands for service" through the feedback from people who had never even put in a support ticket so to prevent this we have changed this to a commercial theme. You can still get the free version at https://github.com/goldhatdev/cobalt.
Cobalt is a responsive theme that integrates the Foundation Framework by Zurb. It uses the Foundation grid to make a fully responsive site layout.
Cobalt integrates Foundation TopNav with Concrete5's Autonav for use as the main site header. A key feature of this main navigation is that on mobile devices it will present a clickable menu button with a vertical drop-down of the menu items while displaying horizontally on larger screens.
Grid templates are provided for Content and HTML blocks so that you can use Foundation grid to align these block types side-by-side. Like any other part of the Cobalt templates these side-by-side grids will collapse into single column on small devices.
Cobalt is now available for contributions or forking at GitHub: https://github.com/goldhatdev/cobalt.
*** Please read the documentation for customizing details especially taking note of the need to set your AutoNav to use the custom "topnav" template if you want the responsive Foundaton topnav ***