:root {
    --primary-color: #4a6dff;
    --secondary-color: #7d90ff;
    --text-color: #333;
    --background-color: #f8f9fa;
    --card-color: #ffffff;
    --border-color: #e0e0e0;
    --hover-color: #f0f4ff;
    --header-gradient-start: #4a6dff;
    --header-gradient-end: #7d90ff;
    --header-text: white;
    --footer-bg: #333;
    --footer-text: white;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --stat-card-bg: #ffffff;
    --stat-icon-color: #4a6dff;
}

[data-theme="dark"] {
    --primary-color: #738aff;
    --secondary-color: #9eadff;
    --text-color: #f0f0f0;
    --background-color: #1a1a1a;
    --card-color: #2a2a2a;
    --border-color: #444;
    --hover-color: #3a3a3a;
    --header-gradient-start: #303b73;
    --header-gradient-end: #445189;
    --header-text: #f0f0f0;
    --footer-bg: #111;
    --footer-text: #f0f0f0;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --stat-card-bg: #2a2a2a;
    --stat-icon-color: #738aff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

header {
    background: linear-gradient(135deg, var(--header-gradient-start), var(--header-gradient-end));
    color: var(--header-text);
    padding: 2rem 0;
    text-align: center;
    box-shadow: 0 2px 5px var(--shadow-color);
    position: relative;
}

header h1 {
    margin-bottom: 0.5rem;
    font-size: 2.5rem;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.theme-toggle {
    position: absolute;
    top: 1rem;
    right: 1rem;
}

#theme-toggle-btn {
    background: none;
    border: none;
    color: var(--header-text);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.3s;
}

#theme-toggle-btn:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .fa-sun {
    display: none;
}

[data-theme="dark"] .fa-moon {
    display: none;
}

.dashboard-section {
    margin: 2rem 0;
    background-color: var(--card-color);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px var(--shadow-color);
}

.dashboard-section h2 {
    margin-bottom: 1rem;
    font-size: 1.5rem;
    color: var(--text-color);
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.stat-card {
    background-color: var(--stat-card-bg);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px var(--shadow-color);
    text-align: center;
    transition: transform 0.2s;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-card i {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--stat-icon-color);
}

.stat-card h3 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.stat-card p {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.search-section {
    margin: 2rem 0;
    background-color: var(--card-color);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px var(--shadow-color);
}

.search-container {
    display: flex;
    margin-bottom: 1rem;
}

.search-container input {
    flex-grow: 1;
    padding: 0.8rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 4px 0 0 4px;
    font-size: 1rem;
    background-color: var(--card-color);
    color: var(--text-color);
}

.search-container button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0 1.5rem;
    cursor: pointer;
    border-radius: 0 4px 4px 0;
    transition: background-color 0.2s;
}

.search-container button:hover {
    background-color: var(--secondary-color);
}

.filter-sorting-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 1rem;
}

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

.filter-container label, .sorting-container label {
    font-weight: 600;
    margin-right: 0.5rem;
    color: var(--text-color);
}

.filter-container select, .sorting-container select {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--card-color);
    color: var(--text-color);
}

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

.articles-section {
    margin-bottom: 3rem;
}

#articles-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.article-card {
    background-color: var(--card-color);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 10px var(--shadow-color);
    transition: transform 0.2s, box-shadow 0.2s;
    display: flex;
    flex-direction: column;
    border: 1px solid var(--border-color);
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px var(--shadow-color);
}

.article-source-icon {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    font-size: 1.5rem;
    color: var(--primary-color);
    opacity: 0.7;
}

.article-header {
    padding: 1.2rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    position: relative;
}

.article-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.article-title a {
    text-decoration: none;
    color: inherit;
}

.article-meta {
    font-size: 0.9rem;
    color: #666;
    display: flex;
    justify-content: space-between;
}

[data-theme="dark"] .article-meta {
    color: #aaa;
}

.article-source {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
}

.article-content {
    padding: 1.5rem;
    flex-grow: 1;
}

.article-summary {
    margin-bottom: 1rem;
    font-size: 0.95rem;
    color: var(--text-color);
    line-height: 1.5;
}

.article-authors {
    margin-bottom: 1rem;
    font-size: 0.9rem;
    color: var(--text-color);
}

.article-keywords {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.keyword {
    background-color: var(--hover-color);
    padding: 0.3rem 0.6rem;
    border-radius: 20px;
    font-size: 0.8rem;
    color: var(--text-color);
    transition: background-color 0.2s;
}

.keyword:hover {
    background-color: var(--primary-color);
    color: white;
    cursor: pointer;
}

.article-links {
    margin-top: 1rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.article-links a {
    display: inline-block;
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 600;
    transition: color 0.2s;
    padding: 0.5rem 0.75rem;
    border-radius: 4px;
    background-color: var(--hover-color);
}

.article-links a:hover {
    background-color: var(--primary-color);
    color: white;
}

.pagination {
    display: flex;
    justify-content: center;
    margin-top: 2rem;
    gap: 0.5rem;
}

.pagination button {
    padding: 0.5rem 1rem;
    background-color: var(--card-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    color: var(--text-color);
    transition: background-color 0.2s;
}

.pagination button:hover {
    background-color: var(--hover-color);
}

.pagination button.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.pagination button:disabled {
    cursor: not-allowed;
    opacity: 0.5;
}

.loading-spinner {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 3rem 0;
}

.spinner {
    border: 4px solid rgba(0, 0, 0, 0.1);
    border-radius: 50%;
    border-top: 4px solid var(--primary-color);
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin-bottom: 1rem;
}

[data-theme="dark"] .spinner {
    border: 4px solid rgba(255, 255, 255, 0.1);
    border-top: 4px solid var(--primary-color);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.hidden {
    display: none;
}

#no-results {
    text-align: center;
    padding: 3rem 0;
    font-size: 1.2rem;
    color: #666;
}

[data-theme="dark"] #no-results {
    color: #aaa;
}

footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 2rem 0;
    text-align: center;
}

footer a {
    color: var(--secondary-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

/* Trend Analysis Section Styles */
.trends-section {
    margin: 2rem 0;
    background-color: var(--card-color);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px var(--shadow-color);
}

.trends-section h2 {
    margin-bottom: 1rem;
    font-size: 1.5rem;
    color: var(--text-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.trends-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.trends-controls select {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--card-color);
    color: var(--text-color);
}

.trend-visualization {
    margin-bottom: 1.5rem;
    position: relative;
    height: 400px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 1rem;
    background-color: var(--background-color);
}

.trend-insights {
    background-color: var(--hover-color);
    padding: 1rem;
    border-radius: 8px;
}

.trend-insights h3 {
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
    color: var(--text-color);
}

#trend-insights-list {
    list-style-type: none;
    padding-left: 0;
}

#trend-insights-list li {
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-color);
}

#trend-insights-list li:before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--primary-color);
}

#keyword-trend-selector select {
    width: 100%;
    min-height: 120px;
    padding: 0.5rem;
}

.time-range-selector,
.trend-type-selector,
#keyword-trend-selector {
    flex: 1;
    min-width: 200px;
}

/* Media queries for responsive trends section */
@media (max-width: 768px) {
    .trends-controls {
        flex-direction: column;
    }
    
    .trend-visualization {
        height: 300px;
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    header p {
        font-size: 1rem;
    }
    
    .filter-container, .sorting-container {
        flex-direction: column;
        align-items: flex-start;
        width: 100%;
    }
    
    .filter-container > *, .sorting-container > * {
        width: 100%;
        margin-bottom: 0.5rem;
    }
    
    #articles-container {
        grid-template-columns: 1fr;
    }
    
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
    
    .theme-toggle {
        position: static;
        margin-top: 1rem;
    }
    
    #theme-toggle-btn {
        margin: 0 auto;
    }
}

/* Attention section styling */
.attention-section {
    background-color: #f9f9f9;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 25px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.attention-section h2 {
    color: #333;
    font-size: 1.5rem;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
}

.attention-section h2 i {
    margin-right: 10px;
    color: #ff5722;
}

.attention-controls {
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.view-selector, .count-selector {
    margin-bottom: 10px;
}

.attention-controls label {
    margin-right: 8px;
    font-weight: 500;
}

.attention-controls select {
    padding: 6px 12px;
    border-radius: 4px;
    border: 1px solid #ddd;
    background-color: white;
}

.attention-visualization {
    height: 300px;
    margin-bottom: 20px;
}

.keyword-ranking {
    background-color: white;
    border-radius: 6px;
    padding: 15px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.keyword-ranking h3 {
    font-size: 1.2rem;
    margin-bottom: 15px;
    color: #444;
}

.keyword-ranking-list {
    max-height: 400px;
    overflow-y: auto;
}

.paper-attention-item {
    padding: 12px;
    border-bottom: 1px solid #eee;
    display: flex;
    align-items: center;
}

.paper-attention-item:last-child {
    border-bottom: none;
}

.paper-attention-item:hover {
    background-color: #f5f5f5;
}

.paper-rank {
    font-weight: bold;
    font-size: 1.1rem;
    margin-right: 15px;
    min-width: 30px;
    color: #666;
}

.paper-rank.top-3 {
    color: #ff5722;
    font-size: 1.3rem;
}

.paper-info {
    flex: 1;
}

.paper-title {
    font-weight: 500;
    margin-bottom: 5px;
}

.paper-title a {
    color: #0066cc;
    text-decoration: none;
}

.paper-title a:hover {
    text-decoration: underline;
}

.paper-meta {
    font-size: 0.85rem;
    color: #666;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.paper-score {
    margin-left: 15px;
    font-weight: bold;
    color: #ff5722;
    font-size: 1.1rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.paper-score-label {
    font-size: 0.75rem;
    color: #888;
    font-weight: normal;
}

[data-theme="dark"] .attention-section {
    background-color: #333;
}

[data-theme="dark"] .attention-section h2,
[data-theme="dark"] .attention-section h3 {
    color: #eee;
}

[data-theme="dark"] .attention-controls select {
    background-color: #444;
    border-color: #555;
    color: #eee;
}

[data-theme="dark"] .keyword-ranking {
    background-color: #3a3a3a;
}

[data-theme="dark"] .paper-attention-item:hover {
    background-color: #444;
}

[data-theme="dark"] .paper-title a {
    color: #77aaff;
}

[data-theme="dark"] .paper-meta {
    color: #bbb;
}

@media (max-width: 768px) {
    .attention-controls {
        flex-direction: column;
    }
    
    .view-selector, .count-selector {
        width: 100%;
        margin-bottom: 10px;
    }
}

/* Tabs styling */
.tabs-container {
    margin-bottom: 25px;
}

.tabs {
    display: flex;
    overflow-x: auto;
    border-bottom: 2px solid #eee;
    position: sticky;
    top: 0;
    background-color: #fff;
    z-index: 100;
}

.tab-button {
    padding: 12px 20px;
    border: none;
    background: none;
    font-size: 1rem;
    font-weight: 500;
    color: #666;
    cursor: pointer;
    transition: all 0.3s ease;
    border-bottom: 3px solid transparent;
    display: flex;
    align-items: center;
    white-space: nowrap;
}

.tab-button i {
    margin-right: 8px;
    font-size: 1.1rem;
}

.tab-button:hover {
    color: #0066cc;
    background-color: #f5f5f5;
}

.tab-button.active {
    color: #0066cc;
    border-bottom-color: #0066cc;
    background-color: #f0f8ff;
}

.tab-content {
    display: none;
    animation: fadeIn 0.3s ease-in;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

[data-theme="dark"] .tabs {
    border-bottom-color: #444;
    background-color: #222;
}

[data-theme="dark"] .tab-button {
    color: #aaa;
}

[data-theme="dark"] .tab-button:hover {
    color: #77aaff;
    background-color: #333;
}

[data-theme="dark"] .tab-button.active {
    color: #77aaff;
    border-bottom-color: #77aaff;
    background-color: #2a3a4a;
}

/* Adjust existing sections to work with tabs */
.trends-section, .attention-section {
    margin-top: 0;
}