<?php
include_once('./_common.php');
$naverpay_button_js = '';
include_once(G5_SHOP_PATH.'/settle_naverpay.inc.php');

// 보관기간이 지난 상품 삭제
cart_item_clean();

$sw_direct = isset($_REQUEST['sw_direct']) ? (int) $_REQUEST['sw_direct'] : 0;

// cart id 설정
set_cart_id($sw_direct);

$s_cart_id = get_session('ss_cart_id');
// 선택필드 초기화
$sql = " update {$g5['g5_shop_cart_table']} set ct_select = '0' where od_id = '$s_cart_id' ";
sql_query($sql);

$cart_action_url = G5_SHOP_URL.'/cartupdate.php';

if(function_exists('before_check_cart_price')) {
    before_check_cart_price($s_cart_id, true, true, true);
}

if (G5_IS_MOBILE) {
    include_once(G5_MSHOP_PATH.'/cart.php');
    return;
}

// 테마에 cart.php 있으면 include
if(defined('G5_THEME_SHOP_PATH')) {
    $theme_cart_file = G5_THEME_SHOP_PATH.'/cart.php';
    if(is_file($theme_cart_file)) {
        include_once($theme_cart_file);
        return;
        unset($theme_cart_file);
    }
}

$g5['title'] = '장바구니';
include_once('./_head.php');
?>

여기에서 include_once('./_head.php'); 이게 어디에 있는 뭘 불러오나요?