default.css에서

/* 메인메뉴 */
#gnb {position:relative;margin:-1px 0 0;border-top:1px dotted #ff3397;border-bottom:1px dotted #ff3397;background:#ffffff}
#gnb h2 {position:absolute;font-size:0;line-height:0;overflow:hidden}
#gnb_1dul {margin:0 auto !important;padding:0;width:970px;zoom:1}
#gnb_1dul:after {display:block;visibility:hidden;clear:both;content:""}
.gnb_1dli {z-index:10;position:relative;float:left}
.gnb_1da {display:inline-block;padding:0 40px 0 10px;height:35px;font-weight:bold;line-height:2.95em;text-decoration:none}
.gnb_1da:focus, .gnb_1da:hover {text-decoration:none}
.gnb_1dli_air .gnb_1da {background-color:#fff}
.gnb_1dli_on .gnb_1da {background-color:#ffffff;color:#ff3397;background:url('../img/gnb_bg01.gif') bottom left no-repeat}
.gnb_2dul {display:none;position:absolute;top:35px;width:125px}
.gnb_2da {display:block;padding:8px 10px;text-align:left;text-decoration:none}
.gnb_1dli_air .gnb_2da {background-color:#333;color:#fff}
.gnb_1dli_on .gnb_2da {border-right:1px dotted #ff3397;border-bottom:1px dotted #ff3397;border-left:1px dotted #ff3397;}
.gnb_2da:focus, .gnb_2da:hover {background:#eef3f5;text-decoration:none}
.gnb_1dli_over .gnb_2dul {border-top:1px dotted #ff3397;display:block;left:0;background:#fff}
.gnb_1dli_over2 .gnb_2dul {display:block;right:0;background:#fff}

head.php에서

 <nav id="gnb">
        <h2>메인메뉴</h2>
        <ul id="gnb_1dul">
            <?php
            $sql = " select *
                        from {$g5['menu_table']}
                        where me_use = '1'
                          and length(me_code) = '2'
                        order by me_order, me_id ";
            $result = sql_query($sql, false);
            $gnb_zindex = 999; // gnb_1dli z-index 값 설정용

            for ($i=0; $row=sql_fetch_array($result); $i++) {
            ?>
            <li class="gnb_1dli" style="z-index:<?php echo $gnb_zindex--; ?>">
                <a href="<?php echo $row['me_link']; ?>" target="_<?php echo $row['me_target']; ?>" class="gnb_1da"><?php echo $row['me_name'] ?></a>
                <?php
                $sql2 = " select *
                            from {$g5['menu_table']}
                            where me_use = '1'
                              and length(me_code) = '4'
                              and substring(me_code, 1, 2) = '{$row['me_code']}'
                            order by me_order, me_id ";
                $result2 = sql_query($sql2);

                for ($k=0; $row2=sql_fetch_array($result2); $k++) {
                    if($k == 0)
                        echo '<ul class="gnb_2dul">'.PHP_EOL;
                ?>
                    <li class="gnb_2dli"><a href="<?php echo $row2['me_link']; ?>" target="_<?php echo $row2['me_target']; ?>" class="gnb_2da"><?php echo $row2['me_name'] ?></a></li>
                <?php
                }

                if($k > 0)
                    echo '</ul>'.PHP_EOL;
                ?>
            </li>
            <?php
            }

            if ($i == 0) {  ?>
                <li id="gnb_empty">메뉴 준비 중입니다.<?php if ($is_admin) { ?> <br><a href="<?php echo G5_ADMIN_URL; ?>/menu_list.php">관리자모드 > 환경설정 > 메뉴설정</a>에서 설정하실 수 있습니다.<?php } ?></li>
            <?php } ?>
        </ul>
    </nav>

어디를 수정해야 합니까?