function show_cart(url) {
  var doc_h = $(document).height();
  var doc_w = $(document).width();
  var win_h = $(window).height();
  var sc_top = $(document).scrollTop();
  var m_left = (doc_w-825)/2;
  
  if (!url) url = '/shop/cart_cl/';

  $("#overlay").css('width',doc_w);
  $("#overlay").css('height',doc_h);
  $("#overlay").show();

  $("#cart_block").css('left',m_left);
  $("#cart_block_content").load(url, function () {
    var m_top = win_h-$("#cart_block").height();
    if (m_top > 0) m_top = m_top/2;
    else m_top = 20;
    if (sc_top > 0) m_top += sc_top;
    $("#cart_block").css('top',m_top);
    $("#cart_block").show();
  });
  return false;
}

function hide_cart() {
  $("#overlay").hide();
  $("#cart_block").hide();
  $("#cart_block_content").empty();
  return false;
}