:root {
            --primary-color: #003366; /* 学术深蓝 */
            --secondary-color: #f4f4f4;
            --accent-color: #c8102e; /* 强调色 */
            --text-color: #333;
            --light-text: #666;
            --border-color: #e0e0e0;
        }

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

        body {
            font-family: 'Roboto', sans-serif;
            line-height: 1.6;
            color: var(--text-color);
            background-color: #fff;
        }

        a {
            text-decoration: none;
            color: var(--primary-color);
            transition: color 0.3s;
        }

        a:hover {
            color: var(--accent-color);
        }

        /* Navigation */
        header {
            background: #fff;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
            position: sticky;
            top: 0;
            z-index: 1000;
        }

        .nav-container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 1rem 2rem;
        }

        .logo {
            font-family: 'Playfair Display', serif;
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
        }

        .logo span {
            font-weight: 300;
            font-size: 1rem;
            color: var(--light-text);
            display: block;
        }

        nav ul {
            display: flex;
            list-style: none;
        }

        nav ul li {
            margin-left: 2rem;
        }

        nav ul li a {
            font-weight: 500;
            text-transform: uppercase;
            font-size: 0.9rem;
            color: var(--text-color);
        }

        nav ul li a:hover {
            color: var(--accent-color);
        }

        /* Mobile Menu Button */
        .menu-toggle {
            display: none;
            font-size: 1.5rem;
            cursor: pointer;
        }

        /* Hero Section */
        .hero {
            background-color: var(--secondary-color);
            padding: 6rem 2rem;
            text-align: center;
            border-bottom: 1px solid var(--border-color);
        }

        .hero h1 {
            font-family: 'Playfair Display', serif;
            font-size: 3rem;
            color: var(--primary-color);
            margin-bottom: 1rem;
        }

        .hero p {
            font-size: 1.2rem;
            color: var(--light-text);
            max-width: 800px;
            margin: 0 auto;
        }

        /* Section Styles */
        section {
            padding: 4rem 2rem;
            max-width: 1200px;
            margin: 0 auto;
        }

        .section-title {
            font-family: 'Playfair Display', serif;
            font-size: 2rem;
            margin-bottom: 2rem;
            color: var(--primary-color);
            border-bottom: 2px solid var(--accent-color);
            display: inline-block;
            padding-bottom: 0.5rem;
        }

        /* News Section */
        .news-item {
            background: #fff;
            border-left: 4px solid var(--accent-color);
            padding: 1rem;
            margin-bottom: 1rem;
            background-color: #fafafa;
        }

        .news-date {
            font-weight: bold;
            color: var(--primary-color);
            font-size: 0.9rem;
        }

        /* Research Grid */
        .research-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
        }

        .project-card {
            border: 1px solid var(--border-color);
            border-radius: 4px;
            overflow: hidden;
            transition: transform 0.3s, box-shadow 0.3s;
            background: #fff;
        }

        .project-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        }

       .project-img {
            position: relative;
            height: 220px;
            background-size: cover;
            background-position: center;
            transition: background-image 0.3s ease;
            overflow: hidden;
            }

        /* Hover overlay */
        .project-overlay {
            position: absolute;
            inset: 0;
            background: rgba(0, 51, 102, 0.85);
            color: #fff;
            opacity: 0;
            transition: opacity 0.3s;
            padding: 1rem;
            display: flex;
            flex-direction: column;
            justify-content: flex-end;
        }

        .project-img:hover .project-overlay {
            opacity: 1;
        }

        .project-tags span {
            display: inline-block;
            font-size: 0.75rem;
            background: rgba(255,255,255,0.2);
            padding: 2px 6px;
            margin-right: 5px;
            border-radius: 3px;
        }

        /* Mobile optimization */
        @media (max-width: 768px) {
            .project-img {
                height: 160px;
                background-image: var(--thumb);
            }
        }

        /* Hover overlay */
        .project-overlay {
            position: absolute;
            inset: 0;
            background: rgba(0, 51, 102, 0.85);
            color: #fff;
            opacity: 0;
            transition: opacity 0.3s;
            padding: 1rem;
            display: flex;
            flex-direction: column;
            justify-content: flex-end;
        }
        
        /* Generating a pattern for placeholders using CSS gradients */
        .project-img.p1 { background: linear-gradient(45deg, #f3f3f3 25%, #e0e0e0 25%, #e0e0e0 50%, #f3f3f3 50%, #f3f3f3 75%, #e0e0e0 75%, #e0e0e0 100%); background-size: 20px 20px; }
        .project-img.p2 { background: radial-gradient(circle, #e0e0e0 10%, transparent 10.01%); background-size: 20px 20px; background-color: #f3f3f3; }
        .project-img.p3 { background: repeating-linear-gradient(45deg, #e0e0e0, #e0e0e0 10px, #f3f3f3 10px, #f3f3f3 20px); }
        .project-img.p4 { background: conic-gradient(from 90deg at 50% 50%, #f3f3f3 0% 25%, #e0e0e0 25% 50%, #f3f3f3 50% 75%, #e0e0e0 75% 100%); background-size: 40px 40px;}

        .project-content {
            padding: 1.5rem;
        }

        .project-content h3 {
            margin-bottom: 0.5rem;
            color: var(--primary-color);
        }

        .project-content p {
            font-size: 0.9rem;
            color: var(--light-text);
            margin-bottom: 1rem;
        }

        .tag {
            display: inline-block;
            background: #eee;
            padding: 2px 8px;
            border-radius: 4px;
            font-size: 0.75rem;
            color: #555;
            margin-right: 5px;
        }

        /* Publications */
        .pub-list {
            list-style: none;
        }

        .pub-item {
            margin-bottom: 1.5rem;
            padding-bottom: 1.5rem;
            border-bottom: 1px solid #eee;
        }

        .pub-title {
            font-weight: bold;
            font-size: 1.1rem;
            color: var(--text-color);
        }

        .pub-authors {
            font-style: italic;
            color: var(--light-text);
            font-size: 0.95rem;
        }

        .pub-venue {
            color: var(--primary-color);
            font-weight: 500;
        }

        .btn-small {
            display: inline-block;
            font-size: 0.8rem;
            padding: 2px 8px;
            border: 1px solid var(--primary-color);
            border-radius: 3px;
            margin-top: 5px;
            margin-right: 5px;
        }

        .btn-small:hover {
            background: var(--primary-color);
            color: #fff;
        }

        /* People Section */
        .people-container {
            display: flex;
            flex-wrap: wrap;
            gap: 2rem;
            align-items: flex-start;
        }

        .pi-card {
            flex: 0 0 250px;
            text-align: center;
        }

        .pi-photo {
            width: 200px;
            height: 200px;
            border-radius: 50%;
            background-color: #ccc;
            margin: 0 auto 1rem;
            object-fit: cover;
            /* Placeholder gradient */
            background: linear-gradient(to bottom right, #ccc, #999);
        }

        .pi-info {
            flex: 1;
        }

        /* Teaching */
        .course-list {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 1.5rem;
        }
        
        .course-item {
            background: #f9f9f9;
            padding: 1rem;
            border-left: 3px solid var(--primary-color);
        }

        /* Footer */
        footer {
            background: var(--primary-color);
            color: #fff;
            padding: 3rem 2rem;
            margin-top: 4rem;
        }

        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
        }

        .footer-info h4 {
            margin-bottom: 1rem;
            font-family: 'Playfair Display', serif;
        }

        .footer-info p {
            font-size: 0.9rem;
            opacity: 0.8;
            margin-bottom: 0.5rem;
        }
        
        .footer-info a {
            color: #fff;
            text-decoration: underline;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .nav-container {
                flex-direction: column;
                align-items: flex-start;
            }

            .menu-toggle {
                display: block;
                position: absolute;
                right: 2rem;
                top: 1.5rem;
            }

            nav ul {
                display: none;
                flex-direction: column;
                width: 100%;
                margin-top: 1rem;
            }

            nav ul.active {
                display: flex;
            }

            nav ul li {
                margin: 0.5rem 0;
            }

            .hero h1 {
                font-size: 2rem;
            }
            
            .people-container {
                flex-direction: column;
                align-items: center;
            }
            
            .pi-info {
                text-align: center;
            }
        }