Com puc obtenir una plantilla per la versió 3.x de Joomla!?
From Joomla! Documentation
Template companies are offering Joomla! 3 templates at present, taking advantage of Joomla! 3's responsive design. Also, please note that some Joomla! 2.5 templates will work in Joomla! 3 without any issues or any changes needed, but some will not. It's best to consult with the template's developer on this.