Is an open source, responsive content management system that you can use to build responsive sites. Respond features a REST API, a lightning-fast Angular-powered UI, Bootstrap 3.0, Polymer-based plugins, multilingual support, and an enhanced data layer using PDO.
http://respondcms.com/
or
https://github.com/madoublet/respond
or
http://beta.respondcms.com/
similar - http://www.queness.com/post/14579/6-lightweight-flexible-php-cms
http://respondcms.com/
or
https://github.com/madoublet/respond
or
http://beta.respondcms.com/
similar - http://www.queness.com/post/14579/6-lightweight-flexible-php-cms