/* ========================================
   LIBRARY PAGE STYLES
   ========================================
   Styles for the chemistry library page displaying
   textbooks, reference books, online resources, and more.
*/

/* ========================================
   LIBRARY HEADER
   ======================================== */

/* Library Hero Section */
.library-hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 3rem 1.5rem;
    text-align: center;
    margin-bottom: 2rem;
    border-radius: 8px;
}

.library-hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.library-hero p {
    font-size: 1.2rem;
    opacity: 0.95;
}

/* ========================================
   FILTERS AND SEARCH
   ======================================== */

/* Filter Container */
.library-filters {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.filter-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
    margin-bottom: 1rem;
}

.filter-row:last-child {
    margin-bottom: 0;
}

.filter-group {
    flex: 1;
    min-width: 200px;
}

.filter-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-color);
    font-size: 0.95rem;
}

.filter-group select,
.filter-group input {
    width: 100%;
    padding: 0.625rem;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    background: var(--bg-color);
    color: var(--text-color);
    font-size: 1rem;
}

.filter-group input {
    padding-left: 2.5rem;
}

.search-wrapper {
    position: relative;
}

.search-icon {
    position: absolute;
    left: 0.75rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-color);
    opacity: 0.6;
}

/* Clear Filters Button */
.clear-filters-btn {
    background: var(--accent-color);
    color: white;
    border: none;
    padding: 0.625rem 1.25rem;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.3s;
    margin-top: 1rem;
}

.clear-filters-btn:hover {
    background: #F57C00;
    transform: translateY(-1px);
}

/* ========================================
   CATEGORY TABS
   ======================================== */

.category-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--border-color);
}

.category-tab {
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    color: var(--text-color);
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.3s;
}

.category-tab:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.category-tab.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* ========================================
   LIBRARY ITEMS GRID
   ======================================== */

.library-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

/* ========================================
   LIBRARY ITEM CARD
   ======================================== */

.library-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    transition: all 0.3s;
    display: flex;
    flex-direction: column;
}

.library-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

/* Item Header */
.item-header {
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.item-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.item-author {
    font-size: 1rem;
    color: var(--text-color);
    opacity: 0.8;
    margin-bottom: 0.25rem;
}

.item-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-color);
    opacity: 0.7;
}

/* Item Body */
.item-body {
    flex: 1;
    margin-bottom: 1rem;
}

.item-description {
    color: var(--text-color);
    line-height: 1.6;
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.item-details {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.item-detail-row {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
}

.item-detail-label {
    font-weight: 600;
    color: var(--text-color);
    opacity: 0.8;
}

.item-detail-value {
    color: var(--text-color);
}

/* Tags */
.item-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.tag {
    background: rgba(33, 150, 243, 0.1);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* Rating */
.item-rating {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.rating-stars {
    color: #FFC107;
    font-size: 1.1rem;
}

.rating-value {
    color: var(--text-color);
    font-weight: 600;
    font-size: 0.95rem;
}

/* Item Footer */
.item-footer {
    margin-top: auto;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.item-link {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 5px;
    text-decoration: none;
    text-align: center;
    font-weight: 500;
    transition: all 0.3s;
    width: 100%;
}

.item-link:hover {
    background: #1976D2;
    transform: translateY(-1px);
}

.item-link.free {
    background: var(--secondary-color);
}

.item-link.free:hover {
    background: #388E3C;
}

/* Badge for Free Resources */
.free-badge {
    display: inline-block;
    background: var(--secondary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 0.5rem;
}

/* Premium Badge */
.premium-badge {
    display: inline-block;
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 0.5rem;
}

/* ========================================
   NO RESULTS MESSAGE
   ======================================== */

.no-results {
    text-align: center;
    padding: 3rem 1.5rem;
    background: var(--card-bg);
    border-radius: 8px;
    margin: 2rem 0;
}

.no-results h3 {
    color: var(--text-color);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.no-results p {
    color: var(--text-color);
    opacity: 0.7;
}

/* ========================================
   LOADING STATE
   ======================================== */

.loading {
    text-align: center;
    padding: 3rem;
    color: var(--text-color);
    font-size: 1.2rem;
}

.loading::after {
    content: '...';
    animation: dots 1.5s steps(4, end) infinite;
}

@keyframes dots {
    0%, 20% { content: '.'; }
    40% { content: '..'; }
    60%, 100% { content: '...'; }
}

/* ========================================
   RESPONSIVE DESIGN
   ======================================== */

@media (max-width: 768px) {
    .library-hero h1 {
        font-size: 2rem;
    }
    
    .library-hero p {
        font-size: 1rem;
    }
    
    .library-grid {
        grid-template-columns: 1fr;
    }
    
    .filter-row {
        flex-direction: column;
    }
    
    .filter-group {
        width: 100%;
    }
    
    .category-tabs {
        gap: 0.5rem;
    }
    
    .category-tab {
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }
}