Desktop vs. Mobile; getting size of the screen

[es_91]

If there is no way to find out whether the screen is a desktop or mobile device, could you be so friendly to build some in?

Also, how about a zoom-to-double-size switch for better display on smaller devices?

Background is, SB pages are almost uncontrollable here on Windows Phone and Android 4.x for the desktop size is always the exact screen resolution (minus bars) and the content is therefore displayed very small.

[the.weavster]

Mozilla suggest looking for the string 'mobi' in navigator.userAgent