/* PDF Gallery Styles */
.pdf-gallery {
    padding: 20px 0;
}

.pdf-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.pdf-item {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid #f0f0f0;
}

.pdf-item:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
}

.pdf-thumbnail {
    position: relative;
    overflow: hidden;
    aspect-ratio: 4/3;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.pdf-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s ease;
}

.pdf-item:hover .pdf-thumbnail img {
    transform: scale(1.1);
}

.pdf-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.pdf-item:hover .pdf-overlay {
    opacity: 1;
}

.pdf-play-icon {
    width: 60px;
    height: 60px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #333;
    transform: scale(0.8);
    transition: transform 0.3s ease;
}

.pdf-item:hover .pdf-play-icon {
    transform: scale(1);
}

.pdf-play-icon svg {
    width: 24px;
    height: 24px;
}

.pdf-info {
    padding: 20px;
}

.pdf-title {
    margin: 0 0 8px 0;
    font-size: 18px;
    font-weight: 600;
    line-height: 1.4;
}

.pdf-title a {
    color: #333;
    text-decoration: none;
    transition: color 0.3s ease;
}

.pdf-title a:hover {
    color: #667eea;
}

.pdf-description {
    margin: 0;
    color: #666;
    font-size: 14px;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.message.info.empty {
    text-align: center;
    padding: 60px 20px;
    background: #f8f9fa;
    border-radius: 8px;
    margin-top: 30px;
}

.message.info.empty span {
    font-size: 18px;
    color: #666;
}

/* Responsive */
@media (max-width: 768px) {
    .pdf-grid {
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: 20px;
    }
    
    .pdf-info {
        padding: 15px;
    }
    
    .pdf-title {
        font-size: 16px;
    }
}