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

body {
    background-color: #f5f7fa;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background: linear-gradient(135deg, #2c3e50, #4a6491);
    color: white;
    padding: 20px;
    text-align: center;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo-container {
    display: flex;
    align-items: center;
}

.logo {
    max-height: 60px;
    margin-right: 15px;
}

.header-text {
    flex-grow: 1;
    text-align: center;
}

h1 {
    font-size: 2.2rem;
    margin-bottom: 5px;
}

.subtitle {
    font-size: 1rem;
    opacity: 0.9;
}

.content {
    display: flex;
    gap: 30px;
    margin-top: 20px;
}

.folders-panel {
    flex: 1;
    background: white;
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
    max-height: 600px;
    overflow-y: auto;
}

.preview-panel {
    flex: 2;
    background: white;
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
    min-height: 600px;
}

.folder-list {
    list-style: none;
}

.folder-item {
    padding: 15px;
    border-bottom: 1px solid #eee;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
}

.folder-item:hover {
    background-color: #f0f5ff;
    border-radius: 5px;
}

.folder-item.active {
    background-color: #e3f2fd;
    border-left: 4px solid #2196f3;
}

.folder-icon {
    color: #ff9800;
    font-size: 1.2rem;
}

.pdf-list {
    list-style: none;
    margin-top: 20px;
}

.pdf-item {
    padding: 15px;
    background-color: #f9f9f9;
    border-radius: 8px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: all 0.3s ease;
}

.pdf-item:hover {
    background-color: #e8f4fc;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.pdf-icon {
    color: #e53935;
    font-size: 1.5rem;
    margin-right: 10px;
}

.pdf-info {
    flex-grow: 1;
}

.pdf-name {
    font-weight: 600;
    color: #2c3e50;
}

.pdf-path {
    font-size: 0.8rem;
    color: #7f8c8d;
    margin-top: 5px;
}

.view-btn {
    background: linear-gradient(135deg, #2196f3, #1976d2);
    color: white;
    border: none;
    padding: 8px 15px;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.view-btn:hover {
    background: linear-gradient(135deg, #1976d2, #1565c0);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(33, 150, 243, 0.3);
}

.empty-state {
    text-align: center;
    padding: 40px 0;
    color: #7f8c8d;
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 15px;
    color: #bdc3c7;
}

@media (max-width: 768px) {
    .content {
        flex-direction: column;
    }
    
    .folders-panel, .preview-panel {
        width: 100%;
    }
    
    header {
        flex-direction: column;
        text-align: center;
    }
    
    .logo-container {
        margin-bottom: 15px;
        justify-content: center;
    }
}