function togglePanel(panelOn, panelOff) {
    $(panelOff).animate({
        opacity: 0.25
    }, 1000, function() {
    // Animation complete.
        $(panelOff).css({ display: 'none' })
        $(panelOn).css({ display: 'block' })
        $(panelOn).animate({
            opacity: 1
        }, 1000, function() {
            // Animation complete.
        });
    });
}