I work with one of the most popular content management systems called Joomla. With thousands of templates to choose from, finding one that works for you will be no problem.
I use premade templates that fits your needs. The design and theme are already set. The hard part is choosing one that you like from the thousands that are available.
What is a content management system:
A content management system is software that keeps track of every piece of content on your Web site, much like your local public library keeps track of books and stores them. Content can be simple text, photos, music, video, documents, or just about anything you can think of. A major advantage of using a CMS is that it requires almost no technical skill or knowledge to manage from the front end. Since the CMS manages all your content, you don't have to, which makes it easier for the end user to manage their site from the front end allowing them to edit, change, delete, publish and unpublish content on the front end.
To give you an example of how powerful this CMS is, even Harvard University (Educational department), University of Notre Dame (Alliance for Catholic Education), The Hill, Linux, MTV Greece, The Fashion Spot