Mobile devices can be developed optimized web pages for these devices, so not just dedicated apps.
The rules of design meant as graphics (colors, contrasts, logo positioning) are always valid , but many concepts and key points of the traditional web design fall in front of mobile devices.
For example take the screen resolution: it’s true that on mobile the user can’t resize the browser window , but it’s also true that for a strong web design, it’s necessary to consider all the resolutions of devices and maximize the space available. This forces us to re-consider the position of the menu, the contact information, the contents in the foreground, the quantity of text.
Moreover with the complete diffusion of the touch navigation system we have to foresee for example keys and links that are easy to click and activate with fingers, less precise of a mouse pointer.
And not to mention the weight of the pages which is a fundamental factor as there’s still a lack of real- flat rates for mobile access.