5. The CSS Router
Toucaan uses a simple router written in plain css to prioritize and load the correct stylesheet for a given class of device. Among other goals, Toucaan's css router splits one massive stylesheet into several smaller device-specific stylesheets according to the matched route, which in turn relies on the axis of orientation, other capabilities, and the intrinsic size of the viewport.
Read more about the makings of A CSS Router with in-depth analysis.
Review of CSS Level 4 Media Queries is recommended.
Read the next chapter on baselining vendor normalization.