/**
 * Research Hub Styles
 * 
 * Professional academic styling for the dynamic Research Hub
 */

/* ============================================
   RESEARCH HUB HEADER
   ============================================ */

.research-hub-header {
    background: linear-gradient(135deg, #1a2332 0%, #2d3e50 100%);
    padding: 80px 0 60px;
    text-align: center;
    color: #fff;
    position: relative;
    overflow: hidden;
}

.research-hub-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        radial-gradient(circle at 20% 50%, rgba(52, 152, 219, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(155, 89, 182, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.research-hub-header .page-title {
    font-family: 'Playfair Display', serif;
    font-size: 3.5rem;
    font-weight: 700;
    margin: 0 0 20px;
    position: relative;
    z-index: 1;
}

.research-hub-header .page-subtitle {
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.8;
    opacity: 0.95;
    position: relative;
    z-index: 1;
}

/* ============================================
   RESEARCH HUB LAYOUT
   ============================================ */

.research-hub-content {
    padding: 60px 0;
    background: #f8f9fa;
}

.research-layout {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 40px;
    align-items: start;
}

/* ============================================
   SIDEBAR FILTERS
   ============================================ */

.research-sidebar {
    position: sticky;
    top: 100px;
}

.filter-section {
    background: #fff;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    margin-bottom: 25px;
}

.filter-section h3 {
    font-family: 'Inter', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 15px;
    color: #2c3e50;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.topic-filters {
    list-style: none;
    margin: 0;
    padding: 0;
}

.topic-filters li {
    margin-bottom: 8px;
}

.topic-filters a {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 12px;
    color: #555;
    text-decoration: none;
    border-radius: 6px;
    transition: all 0.3s ease;
    font-size: 0.95rem;
}

.topic-filters a:hover {
    background: #f0f4f8;
    color: #3498db;
    transform: translateX(5px);
}

.topic-filters a.active {
    background: linear-gradient(135deg, #3498db 0%, #2980b9 100%);
    color: #fff;
    font-weight: 600;
}

.topic-filters .count {
    font-size: 0.85rem;
    opacity: 0.7;
}

/* Search Widget */
.search-section {
    padding-bottom: 25px;
}

.research-search-form {
    display: flex;
    gap: 10px;
    position: relative;
}

.search-field {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e8ecef;
    border-radius: 8px;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    outline: none;
    color: #2c3e50;
}

.search-field:focus {
    border-color: #3498db;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.search-submit {
    background: #3498db;
    border: none;
    color: #fff;
    border-radius: 8px;
    width: 44px;
    cursor: pointer;
    font-size: 1.1rem;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.search-submit:hover {
    background: #2980b9;
    transform: translateY(-1px);
}

/* View Count */
.view-count {
    font-size: 0.85rem;
    color: #7f8c8d;
    background: rgba(0, 0, 0, 0.05);
    padding: 4px 8px;
    border-radius: 4px;
    margin-top: 5px;
    display: inline-block;
}

/* Sidebar Stats */
.research-stats-sidebar {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 25px;
    border-radius: 12px;
    color: #fff;
}

.research-stats-sidebar h3 {
    font-family: 'Inter', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 20px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    margin-bottom: 15px;
    padding-bottom: 15px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.stat-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.9;
    margin-top: 5px;
}

/* ============================================
   PAPERS GRID
   ============================================ */

.research-papers-grid {
    min-height: 400px;
}

.papers-count {
    margin-bottom: 25px;
}

.papers-count p {
    color: #666;
    font-size: 0.95rem;
}

.papers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 30px;
}

/* ============================================
   RESEARCH PAPER CARDS
   ============================================ */

.research-paper-card {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.6);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.research-paper-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
    border-color: rgba(52, 152, 219, 0.3);
}

/* Paper Metadata */
.paper-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    padding-bottom: 12px;
    border-bottom: 2px solid #e8ecef;
    font-size: 0.85rem;
    color: #7f8c8d;
}

.published-date {
    font-weight: 600;
}

.reading-time {
    display: flex;
    align-items: center;
    gap: 5px;
}

.reading-time::before {
    content: '📖';
}

/* Paper Title */
.paper-title {
    font-family: 'Playfair Display', serif;
    font-size: 1.4rem;
    font-weight: 700;
    line-height: 1.4;
    margin: 0 0 15px;
}

.paper-title a {
    color: #2c3e50;
    text-decoration: none;
    transition: color 0.3s ease;
}

.paper-title a:hover {
    color: #3498db;
}

/* Topics */
.paper-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 15px;
}

.topic-badge {
    display: inline-block;
    padding: 5px 12px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #fff;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.3px;
}

/* Excerpt */
.paper-excerpt {
    flex: 1;
    color: #555;
    line-height: 1.7;
    margin-bottom: 15px;
    font-size: 0.95rem;
}

/* Keywords */
.paper-keywords {
    font-size: 0.85rem;
    color: #95a5a6;
    margin-bottom: 20px;
    padding-top: 15px;
    border-top: 1px solid #e8ecef;
}

/* CTA Button */
.paper-actions {
    margin-top: auto;
}

.read-paper-btn {
    display: inline-block;
    padding: 12px 24px;
    background: linear-gradient(135deg, #3498db 0%, #2980b9 100%);
    color: #fff;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(52, 152, 219, 0.3);
}

.read-paper-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(52, 152, 219, 0.4);
    background: linear-gradient(135deg, #2980b9 0%, #3498db 100%);
}

/* ============================================
   PAGINATION
   ============================================ */

.research-pagination {
    margin-top: 50px;
    text-align: center;
}

.research-pagination ul {
    display: inline-flex;
    gap: 10px;
    list-style: none;
    padding: 0;
    margin: 0;
}

.research-pagination li {
    display: inline-block;
}

.research-pagination a,
.research-pagination span {
    display: inline-block;
    padding: 10px 18px;
    background: #fff;
    color: #555;
    text-decoration: none;
    border-radius: 8px;
    border: 1px solid #ddd;
    transition: all 0.3s ease;
    font-weight: 500;
}

.research-pagination a:hover {
    background: #3498db;
    color: #fff;
    border-color: #3498db;
}

.research-pagination .current {
    background: #3498db;
    color: #fff;
    border-color: #3498db;
}

/* ============================================
   NO PAPERS FOUND
   ============================================ */

.no-papers-found {
    text-align: center;
    padding: 80px 20px;
    background: #fff;
    border-radius: 16px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
}

.no-papers-found h2 {
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 15px;
}

.no-papers-found p {
    color: #7f8c8d;
    font-size: 1.1rem;
}

.no-papers-found a {
    color: #3498db;
    text-decoration: none;
    font-weight: 600;
}

.no-papers-found a:hover {
    text-decoration: underline;
}

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

@media (max-width: 1024px) {
    .research-layout {
        grid-template-columns: 1fr;
    }

    .research-sidebar {
        position: static;
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 25px;
    }
}

@media (max-width: 768px) {
    .research-hub-header .page-title {
        font-size: 2.5rem;
    }

    .research-hub-header .page-subtitle {
        font-size: 1rem;
    }

    .papers-grid {
        grid-template-columns: 1fr;
    }

    .research-sidebar {
        grid-template-columns: 1fr;
    }

    .research-hub-header {
        padding: 50px 0 40px;
    }

    .research-hub-content {
        padding: 40px 0;
    }
}

@media (max-width: 480px) {
    .research-hub-header .page-title {
        font-size: 2rem;
    }

    .research-paper-card {
        padding: 20px;
    }

    .paper-title {
        font-size: 1.2rem;
    }
}