$(window).scroll(function() {    
    $('.logo_container, .slogan').css({
        "opacity" : ".1",
        "transition" : "opacity .8s ease-in-out"
    });
});

Check the fiddle: http://jsfiddle.net/2k3hfwo0/2/

$(window).scroll(function() {    
    $('.logo_container, .slogan').css({
        "opacity" : ".1",
        "transition" : "opacity .8s ease-in-out"
    });
});

Check the fiddle: https://jsfiddle.net/2k3hfwo0/2/

$(window).scroll(function() {    
$('.logo_container, .slogan').css({
"opacity": ".1",
"transition": "opacity .8s ease-in-out"
});
});

check the fiddle http://jsfiddle.net/2k3hfwo0/2/

$(window).scroll(function() {    
    $('.logo_container, .slogan').css({
        "opacity" : ".1",
        "transition" : "opacity .8s ease-in-out"
    });
});

Check the fiddle: http://jsfiddle.net/2k3hfwo0/2/