LESS is a stylesheet language, that extends CSS with dynamic behaviours such as variables.
A responsive layout adapts to the size of the viewing device, such as a desktop, smartphone or tablet, versus showing a separate layout.
Joomla is an award-winning content management system (CMS), which enables you to build Web sites and powerful online applications.
A content management system is software that allows you to create and manage webpages easily by separating the creation of your content from the mechanics required to present it on the web. In this site, the content is stored in a database. The look and feel are created by a template. The Joomla! software brings together the template and the content to create web pages.