Do you know what a CSS Framework is? Are you aware of the different CSS Frameworks that are available to you.
Everyone now days in the development community of CMS are talking about responsive design, having a theme/template that is responsive allows your website to show up on any size of screens from your laptop to your smart phone, without the need to build an mobile app.
There are many ways you can go about creating a responsive design, the article Best Responsive CSS Frameworks for Web Design is a good read to get you started.
Myself I use the Bootstrap framework for any web development I’m doing, it is a very clean responsive framework that can be used for any type of web site, there are plenty of developers that are using it in developing themes/templates.