How do I stop my fixed navigation from moving like this when the virtual keyboard opens in Mobile Safari?

http://dansajin.com/2012/12/07/fix-position-fixed/ this is one of the solutions proposed. Seems worth a shot.

In short: set fixed elements to position:absolute when any input is focused and reset them when that element is blurred

.header { 
    position: fixed; 
} 
.footer { 
    position: fixed; 
} 
.fixfixed .header, 
.fixfixed .footer { 
    position: absolute; 
} 

and

if ('ontouchstart' in window) {
    /* cache dom references */ 
    var $body = $('body'); 

    /* bind events */
    $(document)
    .on('focus', 'input', function() {
        $body.addClass('fixfixed');
    })
    .on('blur', 'input', function() {
        $body.removeClass('fixfixed');
    });
}