/* ===========================================================
    Academic Homepage - Stylesheet
    =========================================================== */
 
 /* ---------- CSS Custom Properties ---------- */
 :root {
   --color-primary: #1a3a5c;
   --color-primary-light: #2c5282;
   --color-accent: #e8a838;
   --color-accent-light: #f5d78e;
   --color-bg: #ffffff;
   --color-bg-alt: #f8f9fb;
   --color-bg-card: #ffffff;
   --color-text: #2d3748;
   --color-text-light: #5a6a7e;
   --color-text-muted: #8a9bb0;
   --color-border: #e2e8f0;
   --color-navbar: rgba(255, 255, 255, 0.92);
   --radius-sm: 6px;
   --radius-md: 10px;
   --radius-lg: 16px;
   --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
   --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
   --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.10);
   --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
   --font-sans: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
   --max-width: 960px;
 }
 
 /* ---------- Reset & Base ---------- */
 *, *::before, *::after {
   box-sizing: border-box;
   margin: 0;
   padding: 0;
 }
 
 html {
   scroll-behavior: smooth;
   scroll-padding-top: 72px;
 }
 
 body {
   font-family: var(--font-sans);
   font-size: 16px;
   line-height: 1.7;
   color: var(--color-text);
   background: var(--color-bg);
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
 }
 
 img { max-width: 100%; display: block; }
 a { color: var(--color-primary-light); text-decoration: none; transition: color var(--transition); }
 a:hover { color: var(--color-accent); }
 
 /* ---------- Container ---------- */
 .container {
   width: 100%;
   max-width: var(--max-width);
   margin: 0 auto;
   padding: 0 24px;
 }
 
 /* ===========================================================
    NAVBAR
    =========================================================== */
 .navbar {
   position: fixed;
   top: 0;
   left: 0;
   right: 0;
   z-index: 1000;
   background: var(--color-navbar);
   backdrop-filter: blur(12px);
   -webkit-backdrop-filter: blur(12px);
   border-bottom: 1px solid var(--color-border);
   transition: box-shadow var(--transition);
 }
 
 .navbar.scrolled {
   box-shadow: var(--shadow-sm);
 }
 
 .nav-container {
   display: flex;
   align-items: center;
   justify-content: space-between;
   height: 64px;
 }
 
 .nav-logo {
   font-size: 1.2rem;
   font-weight: 700;
   color: var(--color-primary);
   letter-spacing: -0.02em;
 }
 
 .nav-logo:hover {
   color: var(--color-primary-light);
 }
 
 .nav-links {
   display: flex;
   list-style: none;
   gap: 8px;
 }
 
 .nav-link {
   padding: 8px 14px;
   border-radius: var(--radius-sm);
   font-size: 0.9rem;
   font-weight: 500;
   color: var(--color-text-light);
   transition: background var(--transition), color var(--transition);
 }
 
 .nav-link:hover {
   background: var(--color-bg-alt);
   color: var(--color-primary);
 }
 
 .nav-link.active {
   color: var(--color-primary-light);
   background: rgba(44, 82, 130, 0.08);
 }
 
 /* Hamburger toggle */
 .nav-toggle {
   display: none;
   flex-direction: column;
   justify-content: center;
   align-items: center;
   gap: 5px;
   width: 40px;
   height: 40px;
   background: none;
   border: none;
   cursor: pointer;
   padding: 8px;
   border-radius: var(--radius-sm);
 }
 
 .nav-toggle span {
   display: block;
   width: 22px;
   height: 2px;
   background: var(--color-text);
   border-radius: 2px;
   transition: var(--transition);
 }
 
 .nav-toggle.active span:nth-child(1) {
   transform: rotate(45deg) translate(5px, 5px);
 }
 
 .nav-toggle.active span:nth-child(2) {
   opacity: 0;
 }
 
 .nav-toggle.active span:nth-child(3) {
   transform: rotate(-45deg) translate(5px, -5px);
 }
 
 /* ===========================================================
    HERO
    =========================================================== */
 .hero {
   min-height: 100vh;
   display: flex;
   align-items: center;
   padding: 104px 0 80px;
   background: linear-gradient(160deg, #f0f4f8 0%, #ffffff 60%);
 }
 
 .hero-container {
   display: flex;
   align-items: center;
   gap: 56px;
 }
 
 .hero-photo-wrapper {
   flex-shrink: 0;
 }
 
 .hero-photo {
   width: 200px;
   height: 200px;
   border-radius: 50%;
   overflow: hidden;
   border: 4px solid var(--color-bg);
   box-shadow: var(--shadow-md);
   position: relative;
 }
 
 .hero-photo img {
   width: 100%;
   height: 100%;
   object-fit: cover;
 }
 
 .photo-placeholder {
   width: 100%;
   height: 100%;
   display: flex;
   align-items: center;
   justify-content: center;
   background: var(--color-bg-alt);
   font-size: 3rem;
   color: var(--color-text-muted);
 }
 
 .hero-text {
   flex: 1;
 }
 
 .hero-name {
   font-size: 2.6rem;
   font-weight: 700;
   color: var(--color-primary);
   line-height: 1.2;
   letter-spacing: -0.03em;
   margin-bottom: 8px;
 }
 
 .hero-title {
   font-size: 1.1rem;
   color: var(--color-text-light);
   margin-bottom: 6px;
 }
 
 .hero-affiliation {
   font-size: 0.95rem;
   color: var(--color-text-muted);
   margin-bottom: 20px;
 }
 
 .hero-affiliation i {
   margin-right: 6px;
   color: var(--color-primary-light);
 }
 
 .hero-badges {
   display: flex;
   flex-wrap: wrap;
   gap: 8px;
   margin-bottom: 24px;
 }
 
 .badge {
   display: inline-flex;
   align-items: center;
   gap: 6px;
   padding: 5px 14px;
   font-size: 0.82rem;
   font-weight: 500;
   color: var(--color-primary-light);
   background: rgba(44, 82, 130, 0.08);
   border-radius: 20px;
 }
 
 .badge i {
   font-size: 0.75rem;
 }
 
 .hero-actions {
   display: flex;
   gap: 12px;
   flex-wrap: wrap;
 }
 
 /* ---------- Buttons ---------- */
 .btn {
   display: inline-flex;
   align-items: center;
   gap: 8px;
   padding: 10px 24px;
   font-size: 0.9rem;
   font-weight: 600;
   border-radius: var(--radius-sm);
   cursor: pointer;
   transition: all var(--transition);
   border: 2px solid transparent;
 }
 
 .btn-primary {
   background: var(--color-primary);
   color: #ffffff;
 }
 
 .btn-primary:hover {
   background: var(--color-primary-light);
   color: #ffffff;
   transform: translateY(-1px);
   box-shadow: var(--shadow-md);
 }
 
 .btn-outline {
   background: transparent;
   color: var(--color-primary);
   border-color: var(--color-primary);
 }
 
 .btn-outline:hover {
   background: var(--color-primary);
   color: #ffffff;
   transform: translateY(-1px);
 }
 
 /* ===========================================================
    SECTIONS (General)
    =========================================================== */
 .section {
   padding: 80px 0;
 }
 
 .section-alt {
   background: var(--color-bg-alt);
 }
 
 .section-title {
   font-size: 1.8rem;
   font-weight: 700;
   color: var(--color-primary);
   letter-spacing: -0.02em;
   display: flex;
   align-items: center;
   gap: 14px;
 }
 
 .section-number {
   font-size: 1rem;
   font-weight: 600;
   color: var(--color-accent);
   font-variant-numeric: tabular-nums;
 }
 
 .section-divider {
   width: 48px;
   height: 3px;
   background: var(--color-accent);
   border-radius: 4px;
   margin: 16px 0 32px;
 }
 
 /* ===========================================================
    ABOUT
    =========================================================== */
 .about-content {
   max-width: 720px;
 }
 
 .about-content p {
   margin-bottom: 16px;
   color: var(--color-text-light);
 }
 
 .about-content p:last-child {
   margin-bottom: 0;
 }
 
 /* ===========================================================
    RESEARCH INTERESTS
    =========================================================== */
 .research-grid {
   display: grid;
   grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
   gap: 24px;
 }
 
 .research-card {
   background: var(--color-bg-card);
   border: 1px solid var(--color-border);
   border-radius: var(--radius-md);
   padding: 32px 28px;
   transition: all var(--transition);
 }
 
 .research-card:hover {
   border-color: transparent;
   box-shadow: var(--shadow-md);
   transform: translateY(-4px);
 }
 
 .research-icon {
   width: 48px;
   height: 48px;
   display: flex;
   align-items: center;
   justify-content: center;
   background: rgba(44, 82, 130, 0.08);
   border-radius: var(--radius-sm);
   font-size: 1.3rem;
   color: var(--color-primary-light);
   margin-bottom: 18px;
 }
 
 .research-card h3 {
   font-size: 1.1rem;
   font-weight: 600;
   color: var(--color-primary);
   margin-bottom: 10px;
 }
 
 .research-card p {
   font-size: 0.9rem;
   color: var(--color-text-light);
   line-height: 1.65;
   margin-bottom: 16px;
 }
 
 .research-tags {
   display: flex;
   flex-wrap: wrap;
   gap: 6px;
 }
 
 .tag {
   padding: 3px 10px;
   font-size: 0.78rem;
   font-weight: 500;
   color: var(--color-accent);
   background: rgba(232, 168, 56, 0.10);
   border-radius: 12px;
 }
 
 /* ===========================================================
    PUBLICATIONS
    =========================================================== */
 .pub-filter {
   display: flex;
   flex-wrap: wrap;
   gap: 8px;
   margin-bottom: 32px;
 }
 
 .pub-filter-btn {
   padding: 6px 18px;
   font-size: 0.85rem;
   font-weight: 500;
   border: 1px solid var(--color-border);
   border-radius: 20px;
   background: transparent;
   color: var(--color-text-light);
   cursor: pointer;
   transition: all var(--transition);
 }
 
 .pub-filter-btn:hover {
   border-color: var(--color-primary-light);
   color: var(--color-primary-light);
 }
 
 .pub-filter-btn.active {
   background: var(--color-primary);
   border-color: var(--color-primary);
   color: #ffffff;
 }
 
 .pub-item {
   display: flex;
   gap: 20px;
   padding: 20px 24px;
   border-radius: var(--radius-md);
   border: 1px solid var(--color-border);
   margin-bottom: 14px;
   transition: all var(--transition);
   animation: fadeIn 0.3s ease;
 }
 
 .pub-item.hidden {
   display: none;
 }
 
 .pub-item:hover {
   border-color: transparent;
   box-shadow: var(--shadow-sm);
 }
 
 .pub-year-badge {
   flex-shrink: 0;
   width: 60px;
   height: 36px;
   display: flex;
   align-items: center;
   justify-content: center;
   background: rgba(44, 82, 130, 0.08);
   border-radius: var(--radius-sm);
   font-size: 0.85rem;
   font-weight: 700;
   color: var(--color-primary-light);
 }
 
 .pub-info {
   flex: 1;
 }
 
 .pub-info h3 {
   font-size: 0.95rem;
   font-weight: 600;
   color: var(--color-primary);
   margin-bottom: 4px;
 }
 
 .pub-info h3 a {
   color: inherit;
 }
 
 .pub-info h3 a:hover {
   color: var(--color-primary-light);
 }
 
 .pub-authors {
   font-size: 0.85rem;
   color: var(--color-text-light);
   margin-bottom: 2px;
 }
 
 .pub-authors .highlight {
   font-weight: 600;
 }
 
 .pub-venue {
   font-size: 0.83rem;
   color: var(--color-text-muted);
   font-style: italic;
 }
 
 .pub-links {
   display: flex;
   gap: 12px;
   margin-top: 8px;
 }
 
 .pub-link {
   font-size: 0.8rem;
   font-weight: 500;
   display: inline-flex;
   align-items: center;
   gap: 4px;
   color: var(--color-primary-light);
   padding: 2px 10px;
   border-radius: 12px;
   background: rgba(44, 82, 130, 0.06);
   transition: background var(--transition);
 }
 
 .pub-link:hover {
   background: rgba(44, 82, 130, 0.14);
 }
 
 @keyframes fadeIn {
   from { opacity: 0; transform: translateY(6px); }
   to   { opacity: 1; transform: translateY(0); }
 }
 
 /* ===========================================================
    TIMELINE
    =========================================================== */
 .timeline {
   position: relative;
   padding-left: 32px;
 }
 
 .timeline::before {
   content: '';
   position: absolute;
   top: 8px;
   left: 10px;
   bottom: 8px;
   width: 2px;
   background: var(--color-border);
 }
 
 .timeline-item {
   position: relative;
   padding-bottom: 36px;
 }
 
 .timeline-item:last-child {
   padding-bottom: 0;
 }
 
 .timeline-marker {
   position: absolute;
   left: -32px;
   top: 6px;
   width: 14px;
   height: 14px;
   border-radius: 50%;
   background: var(--color-bg);
   border: 3px solid var(--color-accent);
   transform: translateX(-6px);
 }
 
 .timeline-content {
   background: var(--color-bg-card);
   border: 1px solid var(--color-border);
   border-radius: var(--radius-md);
   padding: 20px 24px;
   transition: box-shadow var(--transition);
 }
 
 .timeline-content:hover {
   box-shadow: var(--shadow-sm);
 }
 
 .timeline-date {
   display: inline-block;
   font-size: 0.8rem;
   font-weight: 600;
   color: var(--color-accent);
   margin-bottom: 6px;
 }
 
 .timeline-content h3 {
   font-size: 1rem;
   font-weight: 600;
   color: var(--color-primary);
   margin-bottom: 2px;
 }
 
 .timeline-sub {
   font-size: 0.9rem;
   color: var(--color-text-light);
   margin-bottom: 4px;
 }
 
 .timeline-content p {
   font-size: 0.88rem;
   color: var(--color-text-muted);
 }
 
 /* ===========================================================
    CONTACT
    =========================================================== */
 .contact-content {
   max-width: 600px;
 }
 
 .contact-intro {
   color: var(--color-text-light);
   margin-bottom: 28px;
 }
 
 .contact-links {
   display: flex;
   flex-direction: column;
   gap: 12px;
 }
 
 .contact-item {
   display: flex;
   align-items: center;
   gap: 14px;
   padding: 14px 20px;
   border: 1px solid var(--color-border);
   border-radius: var(--radius-sm);
   color: var(--color-text-light);
   transition: all var(--transition);
 }
 
 .contact-item:hover {
   border-color: var(--color-primary-light);
   color: var(--color-primary);
   background: rgba(44, 82, 130, 0.03);
   transform: translateX(4px);
 }
 
 .contact-item i {
   width: 24px;
   font-size: 1.1rem;
   color: var(--color-primary-light);
   text-align: center;
 }
 
 .contact-item span {
   font-size: 0.92rem;
   font-weight: 500;
 }
 
 /* ===========================================================
    FOOTER
    =========================================================== */
 .footer {
   padding: 32px 0;
   border-top: 1px solid var(--color-border);
   background: var(--color-bg-alt);
 }
 
 .footer-container {
   display: flex;
   flex-wrap: wrap;
   justify-content: space-between;
   align-items: center;
   gap: 8px;
   font-size: 0.85rem;
   color: var(--color-text-muted);
 }
 
 .footer-built-with i {
   color: #e74c3c;
 }
 
 /* ===========================================================
    RESPONSIVE
    =========================================================== */
 
 /* Tablet */
 @media (max-width: 820px) {
   .hero-container {
     flex-direction: column;
     text-align: center;
     gap: 32px;
   }
 
   .hero-badges {
     justify-content: center;
   }
 
   .hero-actions {
     justify-content: center;
   }
 
   .hero-name {
     font-size: 2.2rem;
   }
 
   .hero-photo {
     width: 160px;
     height: 160px;
   }
 
   .section-title {
     font-size: 1.5rem;
   }
 
   .section {
     padding: 60px 0;
   }
 }
 
 /* Mobile */
 @media (max-width: 640px) {
   .nav-links {
     position: fixed;
     top: 64px;
     left: 0;
     right: 0;
     flex-direction: column;
     background: var(--color-navbar);
     backdrop-filter: blur(12px);
     -webkit-backdrop-filter: blur(12px);
     border-bottom: 1px solid var(--color-border);
     padding: 16px 24px;
     gap: 4px;
     transform: translateY(-110%);
     opacity: 0;
     transition: all 0.3s ease;
   }
 
   .nav-links.open {
     transform: translateY(0);
     opacity: 1;
   }
 
   .nav-link {
     display: block;
     padding: 12px 16px;
     border-radius: var(--radius-sm);
   }
 
   .nav-toggle {
     display: flex;
   }
 
   .hero-name {
     font-size: 1.8rem;
   }
 
   .hero-photo {
     width: 130px;
     height: 130px;
   }
 
   .hero {
     padding: 88px 0 60px;
   }
 
   .section-title {
     font-size: 1.3rem;
   }
 
   .section {
     padding: 48px 0;
   }
 
   .research-grid {
     grid-template-columns: 1fr;
   }
 
   .pub-item {
     flex-direction: column;
     gap: 12px;
   }
 
   .pub-year-badge {
     width: auto;
     display: inline-flex;
     padding: 4px 14px;
     height: auto;
   }
 
   .contact-item {
     padding: 12px 16px;
   }
 
   .footer-container {
     flex-direction: column;
     text-align: center;
   }
 
   .timeline {
     padding-left: 24px;
   }
 
   .timeline-marker {
     left: -24px;
     width: 12px;
     height: 12px;
   }
 }
 
 /* ---------- Smooth scrollbar ---------- */
 ::-webkit-scrollbar {
   width: 8px;
 }
 
 ::-webkit-scrollbar-track {
   background: var(--color-bg-alt);
 }
 
 ::-webkit-scrollbar-thumb {
   background: var(--color-border);
   border-radius: 4px;
 }
 
 ::-webkit-scrollbar-thumb:hover {
   background: var(--color-text-muted);
 }
 
 /* Selection */
 ::selection {
   background: rgba(44, 82, 130, 0.2);
   color: var(--color-primary);
 }