function getScrollXY() {
    var scrOfX = 0, scrOfY = 0;
    if( typeof( window.pageYOffset ) == 'number' ) {
        //Netscape compliant
        scrOfY = window.pageYOffset;
        scrOfX = window.pageXOffset;
    } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
        //DOM compliant
        scrOfY = document.body.scrollTop;
        scrOfX = document.body.scrollLeft;
    } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
        //IE6 standards compliant mode
        scrOfY = document.documentElement.scrollTop;
        scrOfX = document.documentElement.scrollLeft;
    }
    return [ scrOfX, scrOfY ];
}

function getWindowSize() {
    var myWidth = 0, myHeight = 0;
    if( typeof( window.innerWidth ) == 'number' ) {
        //Non-IE
        myWidth = window.innerWidth;
        myHeight = window.innerHeight;
    } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
        //IE 6+ in 'standards compliant mode'
        myWidth = document.documentElement.clientWidth;
        myHeight = document.documentElement.clientHeight;
    } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
        //IE 4 compatible
        myWidth = document.body.clientWidth;
        myHeight = document.body.clientHeight;
    }
    return [ myWidth, myHeight ];
}

function set_top_button(){
    scrollPos =getScrollXY()[1]+20; // Update scrollbar position
    var bar=document.getElementById('top_button');
    if(bar){
        bar.style.top = scrollPos+'px';
    }
}

function set_menu_below() {
    docHeight = getWindowSize()[1]; // Update document height
    scrollPos = getScrollXY()[1]; // Update scrollbar position
    var floater = document.getElementById('floater');
    Yboundary = ((scrollPos + docHeight) - floater.offsetHeight); //하단여백
    floater.style.top = Yboundary+'px';
    set_top_button(scrollPos);
}
addLoadEvent(set_top_button);
window.onscroll=set_top_button;
window.onresize=set_top_button;
/*
addLoadEvent(set_menu_below);
window.onscroll=set_menu_below;
window.onresize=set_menu_below;
*/