Scrollstopping parallax effect not working in Safari

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Javascript

jQuery

safari

My site has a stop-scrolling parallax effect. The code I use to stop the scrolling is:

if ( parseInt($("div#bg").css("top"), 10) <= -0 ) {
    $('#content').css('top', (-0) + 'px');
    $('#logo').css('margin-top', (-142) + 'px');
}

This works fine in Chrome, Firefox and Opera but not so much in Safari. Is there a different code to use in Safari? I know Safari has a bug when it comes to scrolling, but I couldn't quite find an answer for it. Is there a workaround to make it also work in Safari? Or some kind of editor that I can run my code through?