/* Research Papers Directory Styles */
.directory-section {
    padding: 6rem 0;
    background-color: var(--bg-color-light);
}

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

.directory-header {
    text-align: center;
    margin-bottom: 3rem;
}

.directory-header h1 {
    font-size: 2.5rem;
    color: var(--dark-color);
    margin-bottom: 1rem;
}

.directory-header p {
    font-size: 1.1rem;
    color: var(--text-color-light);
    max-width: 800px;
    margin: 0 auto;
}

.directory-filters {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.filter-btn {
    padding: 0.8rem 1.5rem;
    border: 2px solid var(--primary-color);
    border-radius: var(--border-radius-md);
    background: transparent;
    color: var(--primary-color);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary-color);
    color: var(--light-color);
}

.directory-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.paper-card {
    background: var(--bg-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition-medium);
    border: 1px solid var(--gray-200);
}

.paper-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.paper-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.paper-content {
    padding: 1.5rem;
}

.paper-category {
    display: inline-block;
    padding: 0.4rem 1rem;
    background: rgba(53, 99, 233, 0.1);
    color: var(--primary-color);
    border-radius: var(--border-radius-full);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.paper-title {
    font-size: 1.2rem;
    color: var(--dark-color);
    margin-bottom: 0.8rem;
    line-height: 1.4;
}

.paper-meta {
    display: flex;
    gap: 1rem;
    color: var(--text-color-light);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.paper-meta span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.paper-description {
    color: var(--text-color-light);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.paper-actions {
    display: flex;
    gap: 1rem;
}

.paper-btn {
    flex: 1;
    padding: 0.8rem;
    border-radius: var(--border-radius-md);
    text-align: center;
    font-weight: 500;
    transition: var(--transition-fast);
}

.paper-btn.primary {
    background: var(--primary-color);
    color: var(--light-color);
}

.paper-btn.secondary {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.paper-btn:hover {
    transform: translateY(-2px);
}

.pagination {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 3rem;
}

.page-btn {
    padding: 0.8rem 1.2rem;
    border: 2px solid var(--primary-color);
    border-radius: var(--border-radius-md);
    background: transparent;
    color: var(--primary-color);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
}

.page-btn:hover,
.page-btn.active {
    background: var(--primary-color);
    color: var(--light-color);
}

/* Responsive Styles */
@media (max-width: 768px) {
    .directory-grid {
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: 1.5rem;
    }

    .paper-card {
        margin-bottom: 1.5rem;
    }

    .directory-filters {
        flex-wrap: wrap;
    }

    .filter-btn {
        padding: 0.6rem 1.2rem;
    }
}

@media (max-width: 576px) {
    .directory-header h1 {
        font-size: 2rem;
    }

    .paper-image {
        height: 180px;
    }

    .paper-content {
        padding: 1.2rem;
    }

    .paper-title {
        font-size: 1.1rem;
    }

    .paper-actions {
        flex-direction: column;
    }
}