In recent years, a mobile-friendly theme called Bootstrap was developed in the Moodle community and released as an open source theme on https://moodle.org/. Bootstrap is a responsive theme. If you haven't come across the idea of responsive web design before, it is actually very simple. It allows the developer to use the browser's built-in ability to detect the screen width and deliver different layouts for different screen widths. For example, a 1,000 pixel wide screen can support a three-column layout but this can be automatically changed to a two-column layout if the screen is under 600 pixels wide, and when it reaches the smaller smartphone width of 300 pixels then the content can be reworked into a single-column layout.
The Bootstrap theme does exactly this, and will adjust your layouts depending on the user's screen width. If you are using Moodle 2.2 through to 2.4, you can download and use the Bootstrap theme (available on https://moodle.org...