/* 기본 설정 */
body, h1, ul, li { margin: 0; padding: 0; list-style: none; }
body { font-family: 'Pretendard', sans-serif; overflow: hidden; height: 100vh; display: flex; flex-direction: column; }
a { text-decoration: none; color: inherit; }

/* 헤더 레이아웃 */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 5%;
    height: 80px;
    background: #fff;
    border-bottom: 1px solid #eee;
    flex-shrink: 0; /* 헤더 높이 고정 */
}

.logo img { height: 40px; display: block; }

/* 네비게이션 */
.nav-container { display: flex; }
.main-menu > li { position: relative; float: left; padding: 0 20px; }
.main-menu > li > a, .main-menu > li > span {
    font-size: 16px; font-weight: 600; line-height: 80px; cursor: pointer; display: block;
}

/* 서브 메뉴 (드롭다운) */
.sub-menu {
    display: none;
    position: absolute;
    top: 80px;
    left: 50%;
    transform: translateX(-50%);
    background: #fff;
    min-width: 180px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
    border: 1px solid #eee;
    padding: 10px 0;
    z-index: 1000;
}
.sub-menu li a { display: block; padding: 10px 20px; font-size: 14px; }
.sub-menu li a:hover { background: #f8f9fa; color: #007bff; }
.main-menu > li:hover .sub-menu { display: block; }

/* 콘텐츠 영역 (Iframe) */
#content-frame {
    width: 100%;
    flex-grow: 1; /* 남은 화면 전체 차지 */
    border: none;
}