[css] Detect if a browser in a mobile device (iOS/Android phone/tablet) is used

Don't detect mobile devices, go for stationary ones instead.

Nowadays (2016) there is a way to detect dots per inch/cm/px that seems to work in most modern browsers (see http://caniuse.com/#feat=css-media-resolution). I needed a method to distinguish between a relatively small screen, orientation didn't matter, and a stationary computer monitor.

Because many mobile browsers don't support this, one can write the general css code for all cases and use this exception for large screens:

@media (max-resolution: 1dppx) {
    /* ... */
}

Both Windows XP and 7 have the default setting of 1 dot per pixel (or 96dpi). I don't know about other operating systems, but this works really well for my needs.

Edit: dppx doesn't seem to work in Internet Explorer.. use (96)dpi instead.