* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: #cdd5d8;
    color: #333;
    min-height: 100vh;
    overflow: hidden;
}

header {
    background: #cdd5d8;
    color: #4b6382;
    font-weight: bold;
    padding: 15px 20px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    position: relative;
    z-index: 10;
    border-bottom: 1px solid #262d33;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.header-buttons {
    display: flex;
    gap: 10px;
    align-items: center;
}

.nav-buttons {
    display: flex;
    gap: 10px;
}

.nav-btn {
    background: #071739;
    color: white;
    border: none;
    padding: 8px 15px;
    border-radius: 4px;
    cursor: pointer;
    transition: background 0.3s;
}

.nav-btn:hover {
    background: #071739;
}

.nav-btn:disabled {
    background: #95a5a6;
    cursor: not-allowed;
}

h1 {
    font-weight: 400;
    font-size: 22px;
    margin: 0;
    flex-grow: 1;
    text-align: center;
    font-weight: bold;
}

.container {
    display: flex;
    height: calc(100vh - 52px);
}

.sidebar {
    width: 300px;
    background: #4b6382;
    color: white;
    overflow-y: auto;
    padding: 20px 0;
    z-index: 5;
    box-shadow: 2px 0 10px rgba(0,0,0,0.1);
}

.sidebar h2 {
    padding: 0 20px 15px;
    font-size: 18px;
    font-weight: 500;
    border-bottom: 1px solid #262d33;
    margin-bottom: 15px;
}

.tree-menu {
    list-style: none;
    padding-left: 0;
}

.tree-menu ul {
    list-style: none;
    padding-left: 20px;
    display: none;
}

.tree-menu li {
    margin-bottom: 5px;
    position: relative;
}

.tree-menu a {
    display: block;
    color: white;
    text-decoration: none;
    padding: 10px 20px 10px 30px;
    transition: all 0.2s;
    border-left: 4px solid transparent;
}

.tree-menu a:hover, .tree-menu a.active {
    background: #7497c9;
    border-left: 4px solid #fffb0a;
}

.has-children > a:after {
    content: "▼";
    font-size: 10px;
    margin-left: 8px;
    position: absolute;
    right: 15px;
}

.has-children.expanded > a:after {
    content: "▲";
}

.has-children.expanded > ul {
    display: block;
}

.content {
    flex: 1;
    overflow: hidden;
    background: #1a2530;
    position: relative;
}

.slide-container {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.slide-container img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}



#feedbackLink {
    position: absolute;
    top: 12px;
    right: 20px;
    font-size: 18px;
    text-decoration: none;
    color: #4b6382;
    font-size: 16px;
    transition: all 0.3s;
}

#feedbackLink:hover {
    color: #e74c3c;
    transform: scale(1.1);
}

.youtube-btn.hidden, .tpak-btn.hidden {
    display: none;
}

.youtube-icon {
    margin-right: 5px;
    font-weight: bold;
}

/* Header buttons styling */
.youtube-btn, .tpak-btn {
    display: inline-flex;
    align-items: center;
    text-decoration: none;
    padding: 8px 15px;
    border-radius: 4px;
    font-weight: 500;
    transition: all 0.3s ease;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    font-size: 14px;
    white-space: nowrap;
    position: static;
    transform: none;
}

.youtube-btn {
    background: #ff0000;
    color: white;
}

.youtube-btn:hover {
    background: #cc0000;
    transform: translateY(-1px);
}

.tpak-btn {
    background: #ff0000;
    color: white;
}

.tpak-btn:hover {
    background: #cc0000;
    transform: translateY(-1px);
}

.youtube-btn.hidden, .tpak-btn.hidden {
    display: none;
}

.youtube-icon {
    margin-right: 5px;
    font-weight: bold;
}

/* Add this to your existing CSS */
.has-children.expanded > ul {
    display: block;
    background: #106fd4;
    border-left: 2px solid #071739;
    margin: 5px 0;
    border-radius: 0 4px 4px 0;
}

.has-children.expanded > ul li:last-child {
    margin-bottom: 0;
}

.has-children.expanded > ul a {
    padding-left: 40px;
    border-left: 2px solid transparent;
}

.has-children.expanded > ul a:hover {
    background: #7497c9;
    border-left: 2px solid #fffb0a;
}

/* More subtle version */
.has-children.expanded > ul {
    display: block;
    background: #3e516b;
    margin: 3px 0;
    border-radius: 0 3px 3px 0;
    border-left: 2px solid #fffb0a;
}

.has-children.expanded > ul a {
    padding-left: 35px;
}

/* Mobile responsiveness */
@media (max-width: 900px) {
    .container {
        flex-direction: column;
        height: auto;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        max-height: 40vh;
    }
    
    .content {
        height: 60vh;
    }
    
    header {
        flex-direction: column;
        gap: 10px;
    }
    
    .nav-buttons {
        order: 2;
    }
    
    h1 {
        order: 1;
    }
    
    .slide-info {
        order: 3;
        width: 100%;
        margin-top: 10px;
    }
}