:root {
    --sidebar-width: 280px;
    --sidebar-bg: #1a1a1a;
    --sidebar-text: #ecf0f1;
    --active-color: #3498db;
    --hover-color: #2c3e50;
}

body {
    margin: 0;
    padding: 0;
    font-family: 'Pretendard', sans-serif;
    display: flex;
    height: 100vh;
    overflow: hidden; /* 스크롤은 내부 영역에서만 발생 */
}

/* --- 사이드바 (메뉴) --- */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--sidebar-bg);
    color: var(--sidebar-text);
    display: flex;
    flex-direction: column;
    border-right: 1px solid #333;
    transition: transform 0.3s ease;
    z-index: 100;
}

.brand {
    padding: 25px;
    background-color: #111;
    text-align: center;
}

.brand h2 {
    margin: 0;
    font-size: 1.2rem;
    color: var(--active-color);
    letter-spacing: 1px;
}

.brand span {
    font-size: 0.8rem;
    color: #888;
}

.menu-list {
    list-style: none;
    padding: 0;
    margin: 0;
    overflow-y: auto;
}

.menu-item {
    border-bottom: 1px solid #333;
}

.menu-btn {
    display: block;
    width: 100%;
    padding: 15px 25px;
    background: none;
    border: none;
    color: #bbb;
    text-align: left;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

.menu-btn:hover {
    background-color: var(--hover-color);
    color: white;
    padding-left: 30px; /* 호버 시 살짝 이동 효과 */
}

.menu-btn.active {
    background-color: var(--active-color);
    color: white;
    font-weight: bold;
}

/* --- 메인 콘텐츠 (Iframe) --- */
.main-content {
    flex: 1;
    position: relative;
    background-color: white;
}

iframe {
    width: 100%;
    height: 100%;
    border: none;
    display: block;
}

/* --- 모바일 반응형 --- */
.mobile-toggle {
    display: none;
    position: absolute;
    top: 15px;
    left: 15px;
    z-index: 200;
    background: var(--active-color);
    color: white;
    border: none;
    padding: 10px;
    border-radius: 5px;
    cursor: pointer;
}

@media (max-width: 768px) {
    .mobile-toggle { display: block; }
    
    .sidebar {
        position: absolute;
        height: 100%;
        transform: translateX(-100%);
    }

    .sidebar.open {
        transform: translateX(0);
    }
}