Theme auto module switch theme according url path
responsive web design is a cheap solution for web page comatible to pc and mobile, however, mobile device become so important, it is worth to design an independent theme for mobile device.
for example, a typical site may have three theme, one for mobile, one for pc,one for manager, you can configuarate site to change theme following rules
path /pc/ will switch desktop theme
path /mobile/ will switch to mobile theme
path /console/ will switch to manage theme