/theme/community/mobile/head.php 에서 

<nav class="side_menu">

<ul>

<?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);

for ($i=0; $row=sql_fetch_array($result); $i++) {

?>

<li class="mu_title">

<?php

$submenus = '';

$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) {

$submenus .= '<button type="button" class="sub_toggle">하위메뉴</button>'.PHP_EOL;

$submenus .= '<ul class="sub_menu">'.PHP_EOL;

}

$submenus .= '<li><a href="'.$row2['me_link'].'" target="_'.$row2['me_target'].'" class="gnb_2da sub_tit2">'.$row2['me_name'].'</a></li>'.PHP_EOL;

}

if($k > 0)

$submenus .= '</ul>'.PHP_EOL;

if($submenus)

$gnb_class = 'sd_cl';

else

$gnb_class = 'sd_cl';

?>

<a href="<?php echo $row['me_link']; ?>" target="_<?php echo $row['me_target']; ?>" class="<?php echo $gnb_class; ?> sub_tit1"><?php echo $row['me_name'] ?></a>

<?php echo $submenus; ?>

</li>

<?php

}

if ($i == 0) {  ?>

<li id="side_menu_empty">메뉴 준비 중입니다.<?php if ($is_admin) { ?> <br><a href="<?php echo G5_ADMIN_URL; ?>/menu_list.php">관리자모드 &gt; 환경설정 &gt; 메뉴설정</a>에서 설정하세요.<?php } ?></li>

<?php } ?>

</ul>

</nav>

// 아래 부분 추가하기

<style>/* 모바일 우측 상단 메뉴시작시 서브메뉴 열려있게 하기 */

.side_menu ul .mu_title ul{display:block}

</style>