Project Design, Colors, Graphics, Images
CMS's generally have 3 main parts.
Template - For the design and layouts, Responsive & Mobile compliant
Design Layout – Positioning
Positioning those design elements like logo, menus, image slider, video player..etc.
Responsive – Mobile Compliant
Customize frameworks from; RocketTheme, Gavick Pro, YouTheme, YouGrid, Shape5, T3, Bootstrap to name a few.
They are responsive, and compliant to many of the browsers.
Many of my current client listed use responsive template frameworks.