Target-denstiyDpi

http://darkforge.blogspot.com/2010/05/customize-android-browser-scaling-with.html

http://www.quirksmode.org/blog/archives/2010/04/a_pixel_is_not.html

device-dpi:    Use the device's native dpi as target dpi.
low-dpi:       120dpi
medium-dpi:    160dpi, which is also the default as of today
high-dpi:      240dpi
<number>:      We take any number between 70 and 400 as a valid target dpi.