/* CSS Variables */
:root {
    --primary-dark: #1a3a3a;
    --primary-mid: #234545;
    --primary-light: #2d5555;
    --accent-teal: #4a7c7c;
    --text-light: #ffffff;
    --text-muted: rgba(255, 255, 255, 0.85);
    --text-subtle: rgba(255, 255, 255, 0.6);
    --bg-card: rgba(255, 255, 255, 0.05);
    --bg-card-hover: rgba(255, 255, 255, 0.08);
    --border-subtle: rgba(255, 255, 255, 0.1);
    --shadow-soft: 0 4px 20px rgba(0, 0, 0, 0.2);
    --transition: all 0.3s ease;
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Source Sans 3', -apple-system, BlinkMacSystemFont, sans-serif;
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-mid) 50%, var(--primary-light) 100%);
    color: var(--text-light);
    min-height: 100vh;
    line-height: 1.6;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: #ffffff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: #333;
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0.5rem;
}

.nav-menu a {
    color: #555;
    text-decoration: none;
    padding: 0.5rem 1rem;
    font-size: 1.1rem;
    font-weight: 600;
    border-radius: 4px;
    transition: var(--transition);
}

.nav-menu a:hover {
    color: var(--primary-dark);
    background: rgba(26, 58, 58, 0.08);
}

.nav-icons {
    display: flex;
    gap: 0.5rem;
}

.icon-btn {
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    color: #555;
    font-size: 1rem;
    border-radius: 4px;
    transition: var(--transition);
}

.icon-btn:hover {
    background: rgba(0, 0, 0, 0.05);
    color: var(--primary-dark);
}

/* Hamburger Menu */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.hamburger span {
    width: 24px;
    height: 2px;
    background: #333;
    transition: var(--transition);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    padding: 200px 2rem 4rem;
    position: relative;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.wave-bg {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.hero-content {
    max-width: 1100px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 4rem;
    position: relative;
    z-index: 1;
    padding-top: 2rem;
}

/* Profile Section */
.profile-section {
    text-align: center;
}

.profile-image-container {
    position: relative;
    width: 180px;
    height: 180px;
    margin: 0 auto 1.5rem;
}

.profile-image {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid rgba(255, 255, 255, 0.2);
    box-shadow: var(--shadow-soft);
}

.name {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
    letter-spacing: 0.5px;
}

.name-chinese {
    font-family: 'Noto Serif SC', serif;
    font-size: 1.4rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
    letter-spacing: 0.3em;
}

.title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: 0.25rem;
}

.affiliation {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

/* Social Links */
.social-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.social-links a {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-size: 1.1rem;
    border-radius: 50%;
    background: var(--bg-card);
    transition: var(--transition);
}

.social-links a:hover {
    background: var(--bg-card-hover);
    color: var(--text-light);
    transform: translateY(-2px);
}

/* About Section */
.about-section h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    position: relative;
}

.bio-text {
    color: var(--text-muted);
    margin-bottom: 1rem;
    font-size: 1.05rem;
    line-height: 1.7;
}

/* Download Button */
.download-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1.5rem;
    background: rgba(0, 0, 0, 0.3);
    color: var(--text-light);
    text-decoration: none;
    border-radius: 6px;
    font-weight: 500;
    margin: 1.5rem 0 2.5rem;
    border: 1px solid var(--border-subtle);
    transition: var(--transition);
}

.download-btn:hover {
    background: rgba(0, 0, 0, 0.45);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* Info Grid */
.info-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.info-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.info-card h3::before {
    content: '';
    width: 20px;
    height: 20px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2'%3E%3Cpath d='M22 10v6M2 10l10-5 10 5-10 5z'/%3E%3Cpath d='M6 12v5c3 3 9 3 12 0v-5'/%3E%3C/svg%3E");
    background-size: contain;
    opacity: 0.8;
}

.info-card ul {
    list-style: none;
}

.info-card li {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 0.5rem 0;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.info-card li i {
    color: var(--text-subtle);
    font-size: 0.9rem;
    margin-top: 0.2rem;
    width: 18px;
    text-align: center;
}

.info-card li div {
    display: flex;
    flex-direction: column;
}

.info-card li strong {
    color: var(--text-light);
    font-weight: 500;
}

.info-card li span {
    font-size: 0.9rem;
    color: var(--text-subtle);
}

/* Papers Section */
.papers-section {
    background: rgba(0, 0, 0, 0.15);
    padding: 4rem 2rem;
}

.section-container {
    max-width: 900px;
    margin: 0 auto;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.section-title i {
    opacity: 0.8;
}

/* Paper Cards */
.paper-card {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--bg-card);
    border-radius: 8px;
    margin-bottom: 1.25rem;
    border: 1px solid var(--border-subtle);
    transition: var(--transition);
}

.paper-card:hover {
    background: var(--bg-card-hover);
    transform: translateX(4px);
}

.paper-year {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-subtle);
    min-width: 50px;
    padding-top: 0.2rem;
}

.paper-content {
    flex: 1;
}

.paper-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.paper-badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.2rem 0.5rem;
    background: rgba(255, 193, 7, 0.2);
    color: #ffc107;
    border-radius: 4px;
    margin-left: 0.5rem;
    vertical-align: middle;
    text-transform: uppercase;
}

.paper-badge.review {
    background: rgba(100, 181, 246, 0.2);
    color: #64b5f6;
}

.paper-category {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-subtle);
    margin: 2rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-subtle);
}

.paper-category:first-of-type {
    margin-top: 0;
}

.info-card li .year {
    font-size: 0.8rem;
    color: var(--text-subtle);
    margin-top: 0.1rem;
}

.paper-authors {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 0.4rem;
}

.paper-authors strong {
    color: var(--text-light);
}

.paper-venue {
    font-size: 0.9rem;
    color: var(--text-subtle);
    margin-bottom: 0.75rem;
}

.paper-venue i {
    margin-right: 0.4rem;
}

.paper-abstract {
    font-size: 0.9rem;
    color: var(--text-muted);
    line-height: 1.6;
    margin-bottom: 1rem;
}

.paper-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.paper-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.4rem 0.75rem;
    font-size: 0.85rem;
    color: var(--text-muted);
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-subtle);
    border-radius: 4px;
    text-decoration: none;
    transition: var(--transition);
}

.paper-link:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-light);
}

/* Footer */
.footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-subtle);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-subtle);
}

/* Responsive Design */
@media (max-width: 900px) {
    .hero-content {
        grid-template-columns: 1fr;
        gap: 2.5rem;
        text-align: center;
    }
    
    .about-section {
        text-align: left;
    }
    
    .info-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: #ffffff;
        flex-direction: column;
        padding: 1rem;
        gap: 0;
        box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: var(--transition);
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: all;
    }
    
    .nav-menu a {
        display: block;
        padding: 0.75rem 1rem;
    }
    
    .nav-icons {
        display: none;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    .hero {
        padding: 120px 1.5rem 3rem;
    }
    
    .profile-image-container {
        width: 150px;
        height: 150px;
    }
    
    .name {
        font-size: 1.35rem;
    }
    
    .about-section h2 {
        font-size: 1.5rem;
    }
    
    .paper-card {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .paper-year {
        font-size: 0.85rem;
    }
}

/* Animation on scroll */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.profile-section,
.about-section {
    animation: fadeInUp 0.6s ease-out forwards;
}

.about-section {
    animation-delay: 0.2s;
}

.paper-card {
    animation: fadeInUp 0.5s ease-out forwards;
    opacity: 0;
}

.paper-card:nth-child(2) { animation-delay: 0.1s; }
.paper-card:nth-child(3) { animation-delay: 0.2s; }
.paper-card:nth-child(4) { animation-delay: 0.3s; }