const top_space = 50;
const bottom_space = 50;

function left_menu_scroll_event(){
	var device = ($(window).width()>1100)?'pc':'m';
	var header_bottom = $(window).scrollTop()+$('#header').height() + top_space;
	var menu_top = $('#left_menu_container').offset().top;
	var menu_bottom = header_bottom + $('#left_menu_wrap').height();
	var footer_top = $('#footer_'+device).offset().top - bottom_space;

	if(header_bottom > menu_top){
		if(menu_bottom < footer_top)
			$('#left_menu_wrap').css({'margin-top': header_bottom - menu_top});
	}
	else
		$('#left_menu_wrap').css({'margin-top': 0});
}

$(function(){
	$('.n_contents>.container>.row>.col-sm-3').attr('id', "left_menu_container");
	$('#left_menu_container').children().wrapAll('<div id="left_menu_wrap"></div>');

	$(window).scroll(left_menu_scroll_event);
	$(window).resize(left_menu_scroll_event);
	$(window).scroll();

});