The topic of this paper is the problem of spanning a single web design across multiple devices with diffrent screen resolutions, in other words, responsive web design. Responsive web design is a convetion among designers, realised using fluid layouts, flexible images, CSS media queries and support for different screen resolutions by defining size of elements in relative units. In the corresponding practical part of the research, an example web application was made using responsive web design concept, with the procedure documented and later on explained in the paper. Therefore, in the practical part of research for the paper, methods of custom design were made, according to the proposed responsive concept. On the other hand, an abundance of versatile tools and existing solutions for the responsive design implementation are accessible on the web, which provide web designers or common developers to build a fully responsive web site. The main tool for building responsive websites described in this paper is Bootstrap framework, which was also used for the practical part of the research. Bootstrap is one of numerous responsive webkit tools for responsive design available, but besides Bootstrap among most frequently used tools are certainly Wordpress, Drupal, Joomla, Foundation which were also further described in the paper. As Internet traffic over mobile phones continues to increase, so does the need for adjusting web content for devices of smaller screen resolutions. As a result, it is safe to say that responsive web design will surely continue to evolve and many exciting solutions are expected to emerge from that area of design.