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

 :root {
     --primary-color: #1e40af;
     --primary-light: #3b82f6;
     --primary-dark: #1e3a8a;
     --secondary-color: #0f172a;
     --text-primary: #0f172a;
     --text-secondary: #64748b;
     --text-tertiary: #94a3b8;
     --background: #f1f5f9;
     --card-background: #ffffff;
     --border-color: #e2e8f0;
     --hover-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
 }

 body {
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
     min-height: 100vh;
     color: var(--text-primary);

     /* 径向渐变背景：中心浅蓝 → 边缘纯白 */
     background: radial-gradient(ellipse at 50% 50%, #e0f2fe 0%, #f0f8ff 30%, #ffffff 60%);
     background-attachment: fixed;
     /* 固定背景，不随滚动移动 */
 }

/* 中文部分：黑色 */
.brand-cn {
    color: #111827;
    /* 深黑，接近纯黑 */
}

/* 英文部分：浅蓝色，与背景渐变中心色协调 */
.brand-en {
    color: #1666c2
    /* 柔和的浅蓝色，可根据背景微调 */
}

/* 分隔符：可以与英文同色或稍浅，此处与英文同色 */
.brand-sep {
    color: #1666c2;
    margin: 0 4px;
    /* 可选：加一点间距 */
}

 .container {
     max-width: 1400px;
     margin: 0 auto;
     padding: 40px 20px;
 }

 /* Header with Gradient Background */
 .header {
     border-radius: 16px;
     padding: 40px;
     text-align: center;
     margin-bottom: 40px;
 }

 .header h1 {
     font-size: 2.8em;
     color: #1e3a8a;
     margin-bottom: 12px;
     font-weight: 700;
     letter-spacing: 0.5px;
     text-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
     font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', sans-serif;
 }

 .header p {
     font-size: 1.2em;
     color: #475569;
     margin-bottom: 24px;
     font-weight: 400;
     letter-spacing: 1px;
 }

 .refresh-btn {
     background: white;
     color: var(--primary-color);
     border: none;
     padding: 14px 32px;
     font-size: 1.1em;
     border-radius: 8px;
     cursor: pointer;
     font-weight: 600;
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
 }

 .refresh-btn:hover {
     transform: translateY(-2px);
     box-shadow: 0 8px 12px rgba(0, 0, 0, 0.15);
 }

 .refresh-btn:active {
     transform: translateY(0);
 }

 .refresh-btn:disabled {
     opacity: 0.6;
     cursor: not-allowed;
     transform: none;
 }

 /* Layout Container */
 .main-layout {
     display: flex;
     gap: 32px;
     min-height: calc(100vh - 80px);
 }

 /* Sidebar */
 .sidebar {
     width: 280px;
     background: var(--card-background);
     border-radius: 12px;
     padding: 32px 24px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
     border: 1px solid var(--border-color);
     flex-shrink: 0;
     height: fit-content;
     position: sticky;
     top: 40px;
 }

 .sidebar h3 {
     font-size: 1.2em;
     font-weight: 600;
     color: var(--text-primary);
     margin-bottom: 24px;
     padding-bottom: 16px;
     border-bottom: 2px solid var(--border-color);
 }

 .filter-group {
     margin-bottom: 24px;
 }

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

 .filter-group label {
     display: block;
     font-size: 0.9em;
     color: var(--text-secondary);
     margin-bottom: 8px;
     font-weight: 500;
     text-transform: uppercase;
     letter-spacing: 0.5px;
 }

 .filter-group select {
     width: 100%;
     padding: 12px 16px;
     border: 2px solid var(--border-color);
     border-radius: 8px;
     font-size: 1em;
     background: white;
     color: var(--text-primary);
     transition: border-color 0.2s;
     cursor: pointer;
 }

 .filter-group select:focus {
     outline: none;
     border-color: var(--primary-light);
 }

 /* 个人信息和功能描述模块 */
 .info-section {
     margin-top: 32px;
     padding-top: 24px;
     border-top: 2px solid var(--border-color);
 }

 .info-title {
     font-size: 1.1em;
     font-weight: 600;
     color: var(--text-primary);
     margin-bottom: 16px;
     display: flex;
     align-items: center;
     gap: 8px;
 }

 .info-content {
     font-size: 0.9em;
     color: var(--text-secondary);
     line-height: 1.6;
     margin-bottom: 16px;
 }

 .info-links {
     display: flex;
     flex-direction: column;
     gap: 12px;
 }

 .info-links a {
     color: var(--primary-light);
     text-decoration: none;
     font-size: 0.9em;
     display: inline-flex;
     align-items: center;
     gap: 8px;
     transition: color 0.2s;
 }

 .info-links a:hover {
     color: var(--primary-dark);
     text-decoration: underline;
 }

 /* Content Area */
 .content-area {
     flex: 1;
     min-width: 0;
 }

 /* Stats Section */
 .stats {
     font-size: 1.3em;
     font-weight: 600;
     color: var(--text-primary);
     margin-bottom: 32px;
     text-align: center;
     padding: 20px;
     background: white;
     border-radius: 12px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
 }

 /* Papers Grid */
 .papers-grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
 }

/* 亮点两列网格 */
.highlights-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2px 16px;
    margin-top: 4px;
}

/* 让标题跨两列，不影响网格 */
.paper-highlights h4 {
    grid-column: 1 / -1;
    /* 标题独占一行 */
}

 .paper-english-title {
     font-size: 1.15em;
     font-weight: 500;
     color: var(--text-primary);
     margin-bottom: 2px;
     line-height: 1.4;
 }

 .paper-chinese-title {
     font-size: 1.15em;
     font-weight: 700;
     color: var(--primary-dark);
     margin-bottom: 8px;
     line-height: 1.4;
 }

.paper-link-btn {
    display: inline-block;
    margin-top: 8px;
    padding: 6px 16px;
    background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%);
    color: white;
    border-radius: 6px;
    text-decoration: none;
    font-size: 0.9em;
    font-weight: 500;
    transition: background 0.2s;
}

.paper-link-btn:hover {
    background: linear-gradient(135deg, #1e40af 0%, #1e3a8a 100%);
    text-decoration: none;
    color: white;
}

 /* Paper Card */
 .paper-card {
     background: var(--card-background);
     border-radius: 12px;
     padding: 18px 22px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     border: 1px solid var(--border-color);
 }

 .paper-card:hover {
     transform: translateY(-4px);
     box-shadow: var(--hover-shadow);
 }

 .paper-title {
     font-size: 1.4em;
     font-weight: 600;
     color: var(--text-primary);
     margin-bottom: 16px;
     line-height: 1.4;
 }

 .paper-meta {
     font-size: 1em;
     color: var(--text-secondary);
     margin-bottom: 12px;
     display: flex;
     align-items: center;
     gap: 10px;
 }

 .meta-item {
     display: flex;
     align-items: center;
     gap: 6px;
 }

 .paper-abstract {
     font-size: 0.98em;
     color: var(--text-primary);
     line-height: 1.6;
     margin-bottom: 20px;
     display: -webkit-box;
     -webkit-line-clamp: 3;
     -webkit-box-orient: vertical;
     overflow: hidden;
 }

 /* Translation Section */
 .paper-translation {
     font-size: 0.98em;
     color: var(--text-secondary);
     margin-bottom: 20px;
     background: #f8fafc;
     padding: 16px;
     border-radius: 8px;
     border-left: 4px solid var(--primary-light);
 }

 .translation-title {
     font-weight: 600;
     margin-bottom: 10px;
     color: var(--text-primary);
 }

 /* Highlights Section */
 .paper-highlights {
     margin-bottom: 20px;
 }

 .paper-highlights h4 {
     font-size: 1em;
     font-weight: 600;
     color: var(--text-primary);
     margin-bottom: 6px;
     display: flex;
     align-items: center;
     gap: 8px;
 }

 .highlight-item {
     font-size: 0.9em;
     color: var(--text-secondary);
     margin-bottom: 2px;
     padding-left: 20px;
     position: relative;
     line-height: 1.4;
 }

 .highlight-item::before {
     content: "•";
     position: absolute;
     left: 6px;
     color: var(--primary-light);
 }

 /* Categories Section */
 .paper-categories {
     margin-bottom: 12px;
 }

 .paper-categories h4 {
     font-size: 0.95em;
     font-weight: 600;
     color: #374151;
     margin-bottom: 8px;
     display: flex;
     align-items: center;
     gap: 6px;
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
     letter-spacing: 0.3px;
 }

 .category-tag {
     display: inline-block;
     background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%);
     color: white;
     padding: 6px 16px;
     border-radius: 20px;
     font-size: 0.9em;
     margin-right: 8px;
     margin-bottom: 8px;
     font-weight: 500;
     transition: all 0.2s;
 }

 .category-tag:hover {
     transform: scale(1.05);
     box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
 }

 .category-tag.primary {
     background: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%);
 }

 .category-tag.secondary {
     background: linear-gradient(135deg, #8b5cf6 0%, #6d28d9 100%);
 }

 .category-tag.tertiary {
     background: linear-gradient(135deg, #06b6d4 0%, #0891b2 100%);
 }

 .category-tag.quaternary {
     background: linear-gradient(135deg, #10b981 0%, #059669 100%);
 }

 .category-tag.quinary {
     background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
 }

 /* Paper Link Section */
 .paper-link-section {
     display: flex;
     align-items: center;
     gap: 12px;
     margin-top: 16px;
     padding-top: 16px;
     border-top: 1px solid var(--border-color);
 }

 .paper-link {
     color: var(--primary-light);
     text-decoration: none;
     font-size: 1em;
     font-weight: 500;
     transition: color 0.2s;
 }

 .paper-link:hover {
     color: var(--primary-dark);
     text-decoration: none;
 }

 .category-info {
     font-size: 0.85em;
     color: var(--text-tertiary);
     padding: 4px 12px;
     background: #f8fafc;
     border-radius: 16px;
     white-space: nowrap;
 }
 
 .multi-select {
     position: relative;
 }

 .multi-select-button {
     width: 100%;
     padding: 10px 14px;
     border: 2px solid var(--border-color);
     border-radius: 8px;
     background: white;
     text-align: left;
     cursor: pointer;
     font-size: 0.95em;
     color: var(--text-primary);
 }

 .multi-select-dropdown {
     position: absolute;
     top: 100%;
     left: 0;
     right: 0;
     background: white;
     border: 2px solid var(--border-color);
     border-radius: 8px;
     max-height: 250px;
     overflow-y: auto;
     z-index: 100;
     margin-top: 4px;
     padding: 4px 0;
 }

 .multi-select-dropdown label {
     display: block;
     padding: 6px 12px;
     cursor: pointer;
     font-weight: normal;
     font-size: 0.9em;
     text-transform: none;
     letter-spacing: normal;
 }

 .multi-select-dropdown label:hover {
     background: #f1f5f9;
 }

 .multi-select-dropdown input[type="checkbox"] {
     margin-right: 8px;
     vertical-align: middle;
 }

 /* Loading and Empty States */
 .loading {
     text-align: center;
     color: var(--text-secondary);
     font-size: 1.3em;
     margin: 60px 0;
 }

 .empty {
     text-align: center;
     color: var(--text-secondary);
     font-size: 1.3em;
     margin: 60px 0;
     background: white;
     padding: 40px;
     border-radius: 12px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
 }

 /* Pagination Styles */
 .pagination-container {
     background: var(--card-background);
     border-radius: 12px;
     padding: 24px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
     border: 1px solid var(--border-color);
 }

 .pagination-info {
     font-size: 1.1em;
     color: var(--text-secondary);
     margin-bottom: 20px;
 }

 .pagination-controls {
     display: flex;
     align-items: center;
     justify-content: center;
     gap: 16px;
 }

 .pagination-btn {
     background: var(--primary-light);
     color: white;
     border: none;
     padding: 10px 20px;
     border-radius: 8px;
     font-size: 1em;
     cursor: pointer;
     transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
     font-weight: 500;
 }

 .pagination-btn:hover:not(:disabled) {
     background: var(--primary-dark);
     transform: translateY(-2px);
     box-shadow: 0 4px 12px rgba(30, 64, 175, 0.3);
 }

 .pagination-btn:disabled {
     background: var(--text-tertiary);
     cursor: not-allowed;
     opacity: 0.6;
 }

 .pagination-numbers {
     display: flex;
     gap: 8px;
 }

 .page-number {
     background: var(--background);
     color: var(--text-primary);
     border: 2px solid var(--border-color);
     padding: 8px 16px;
     border-radius: 8px;
     cursor: pointer;
     transition: all 0.2s;
     font-weight: 500;
     min-width: 40px;
     text-align: center;
 }

 .page-number:hover {
     border-color: var(--primary-light);
     background: white;
 }

 .page-number.active {
     background: var(--primary-light);
     color: white;
     border-color: var(--primary-light);
 }

 /* Responsive Design */
 @media (max-width: 768px) {
     .main-layout {
         flex-direction: column;
     }

     .sidebar {
         width: 100%;
         position: static;
         margin-bottom: 24px;
     }

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

     .pagination-controls {
         flex-wrap: wrap;
         gap: 12px;
     }

     .pagination-numbers {
         order: -1;
         width: 100%;
         justify-content: center;
     }
 }

 /* 底部信息栏 */
 .footer-info {
     display: flex;
     flex-wrap: wrap;
     justify-content: space-between;
     gap: 30px;
     margin-top: 60px;
     padding: 40px 20px;
     background: var(--card-background);
     border-radius: 12px;
     border-top: 1px solid var(--border-color);
 }

 .footer-column {
     flex: 1;
     min-width: 200px;
 }

 .footer-column h3 {
     font-size: 1.2em;
     margin-bottom: 15px;
     color: var(--text-primary);
     border-left: 4px solid var(--primary-light);
     padding-left: 12px;
 }

 .footer-column p,
 .footer-column ul {
     font-size: 0.9em;
     color: var(--text-secondary);
     line-height: 1.6;
 }

 .footer-column:first-child h3:not(:first-of-type) {
     margin-top: 5px;
     /* 控制上方间距，可根据需要调整数值 */
 }

 /* 单独调大作者信息栏（第一列）和项目统计栏（第三列）的文字 */
 .footer-column:first-child p,
 .footer-column:first-child ul,
 .footer-column:last-child p,
 .footer-column:last-child ul {
     font-size: 1.05em;
     /* 调大，可改为 1.1em */
     color: #1f2937;
     /* 可选：颜色加深一点 */
 }

 /* 如果希望列表项也调大 */
 .footer-column:first-child li,
 .footer-column:last-child li {
     font-size: 1.05em;
 }

 .footer-column ul {
     padding-left: 20px;
 }

 .qrcode-placeholder {
     text-align: center;
 }

 .qrcode-placeholder img {
     width: 200px;
     border-radius: 8px;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
 }

 @media (max-width: 768px) {
     .footer-info {
         flex-direction: column;
         text-align: center;
     }

     .footer-column h3 {
         border-left: none;
         border-bottom: 2px solid var(--primary-light);
         display: inline-block;
         padding-bottom: 5px;
     }
 }

 /* 期刊分组样式 */
 .journal-group {
     margin-bottom: 18px;
 }

 .journal-group h4 {
     font-size: 0.95em;
     font-weight: 600;
     margin: 0 0 8px 0;
     color: var(--primary-light);
     border-left: 3px solid var(--primary-light);
     padding-left: 10px;
 }

 .journal-list {
     list-style: none;
     padding-left: 0;
     margin: 0;
     display: flex;
     flex-wrap: wrap;
     gap: 6px 20px;
 }

 .journal-list li {
     font-size: 0.85em;
     color: var(--text-secondary);
     width: calc(50% - 10px);
     /* 两列，行内间距 */
 }

 /* 窄屏幕时单列 */
 @media (max-width: 768px) {
     .journal-list li {
         width: 100%;
     }
 }
 
 /* 加载动画 */
 @keyframes spin {
     0% {transform: rotate(0deg);}
     100% {transform: rotate(360deg);}
 }
 
 /* 默认折叠区域隐藏 */
 .card-expanded-content {
     max-height: 0;
     overflow: hidden;
     transition: max-height 0.3s ease;
 }

 /* 展开时显示 */
 .expandable-card.expanded .card-expanded-content {
     max-height: 600px;
     /* 足够大以容纳内容 */
 }

 /* 卡片鼠标变为手型，提示可点击 */
 .expandable-card {
     cursor: pointer;
     transition: box-shadow 0.2s;
 }

 .expandable-card:hover {
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
 }

 /* 已展开的卡片加点背景区分（可选） */
 .expandable-card.expanded {
     background-color: #fcfcfc;
 }