function setContentAlpha() {
    document.getElementById('case_up').style.opacity = 0;
    document.getElementById('case_middle').style.opacity = 0;
    document.getElementById('case_down').style.opacity = 0;
}

function contentFadeIn() {
    var alphaContent1 = parseFloat(document.getElementById('case_up').style.opacity);
    alphaContent1 = alphaContent1 + 0.05;
    document.getElementById('case_up').style.opacity = alphaContent1;
    document.getElementById('case_middle').style.opacity = alphaContent1;
    document.getElementById('case_down').style.opacity = alphaContent1;

    if (document.getElementById('case_up').style.opacity < 0.99) {
        idAlpha = setTimeout("contentFadeIn()",20)
    } else {
        document.getElementById('case_up').style.opacity = 1;
        document.getElementById('case_middle').style.opacity = 1;
        document.getElementById('case_down').style.opacity = 1;
        clearInterval(idAlpha);
    }
}

function contentFader() {
    var e1 = document.getElementById('case_up');
    var e2 = document.getElementById('case_middle');
    var e3 = document.getElementById('case_down');
    
    if (e1 != null && e2 != null && e3 != null) {
        setContentAlpha();
        contentFadeIn();
    }        
}