/* ============================================
   CSS VARIABLES & THEME
   ============================================ */
:root {
    --font-heading: 'Playfair Display', Georgia, serif;
    --font-body: 'Source Sans 3', 'Segoe UI', sans-serif;

    /* Light Mode */
    --bg-primary: #FAFBFD;
    --bg-secondary: #FFFFFF;
    --bg-tertiary: #F0F3F8;
    --bg-nav: rgba(250, 251, 253, 0.92);
    --text-primary: #1A2332;
    --text-secondary: #4A5568;
    --text-tertiary: #718096;
    --accent: #1B3A5C;
    --accent-light: #2C5282;
    --accent-lighter: #E8EEF5;
    --accent-glow: rgba(27, 58, 92, 0.08);
    --border: #E2E8F0;
    --border-light: #EDF2F7;
    --card-shadow: 0 1px 3px rgba(0,0,0,0.06), 0 4px 16px rgba(0,0,0,0.04);
    --card-hover-shadow: 0 4px 12px rgba(0,0,0,0.08), 0 8px 32px rgba(0,0,0,0.06);
    --tag-bg: #E8EEF5;
    --tag-text: #1B3A5C;
    --hero-gradient: linear-gradient(160deg, #0F2440 0%, #1B3A5C 40%, #2C5282 100%);
    --footer-bg: #0F2440;
    --badge-published: #C6F6D5;
    --badge-published-text: #22543D;
    --badge-review: #FEFCBF;
    --badge-review-text: #744210;
    --badge-conference: #BEE3F8;
    --badge-conference-text: #2A4365;
}

[data-theme="dark"] {
    --bg-primary: #0D1B2A;
    --bg-secondary: #132338;
    --bg-tertiary: #1A2E45;
    --bg-nav: rgba(13, 27, 42, 0.95);
    --text-primary: #E8EEF5;
    --text-secondary: #A0B4CC;
    --text-tertiary: #6B8AAF;
    --accent: #5B9BD5;
    --accent-light: #7CB3E0;
    --accent-lighter: #1A2E45;
    --accent-glow: rgba(91, 155, 213, 0.1);
    --border: #1E3A54;
    --border-light: #162D44;
    --card-shadow: 0 1px 3px rgba(0,0,0,0.2), 0 4px 16px rgba(0,0,0,0.15);
    --card-hover-shadow: 0 4px 12px rgba(0,0,0,0.3), 0 8px 32px rgba(0,0,0,0.2);
    --tag-bg: #1A2E45;
    --tag-text: #5B9BD5;
    --hero-gradient: linear-gradient(160deg, #060E18 0%, #0D1B2A 40%, #132338 100%);
    --footer-bg: #060E18;
    --badge-published: #1C3D2E;
    --badge-published-text: #68D391;
    --badge-review: #3D3419;
    --badge-review-text: #ECC94B;
    --badge-conference: #1A3550;
    --badge-conference-text: #63B3ED;
}

/* ============================================
   RESET & BASE
   ============================================ */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-body);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.7;
    font-size: 16px;
    transition: background-color 0.4s ease, color 0.4s ease;
    overflow-x: hidden;
}

h1, h2, h3, h4 {
    font-family: var(--font-heading);
    line-height: 1.3;
}

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

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

img {
    max-width: 100%;
    height: auto;
}

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
}

section {
    padding: 80px 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5em;
    color: var(--text-primary);
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -6px;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--accent);
    border-radius: 2px;
}

.section-subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 2.5em;
    max-width: 600px;
}

/* ============================================
   NAVIGATION
   ============================================ */
nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: var(--bg-nav);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-light);
    transition: background 0.4s ease, box-shadow 0.3s ease;
}

nav.scrolled {
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
}

.nav-inner {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav-logo {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 28px;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    letter-spacing: 0.01em;
    position: relative;
    padding: 4px 0;
    transition: color 0.3s ease;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: width 0.3s ease;
    border-radius: 1px;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--accent);
}

.nav-links a.active::after,
.nav-links a:hover::after {
    width: 100%;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 36px;
    height: 36px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    color: var(--text-primary);
    font-size: 1.5rem;
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    background: var(--hero-gradient);
    padding: 140px 0 80px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(ellipse at 70% 20%, rgba(255,255,255,0.04) 0%, transparent 60%),
                radial-gradient(ellipse at 20% 80%, rgba(255,255,255,0.02) 0%, transparent 50%);
    pointer-events: none;
}

.hero-inner {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    gap: 60px;
}

.hero-photo {
    flex-shrink: 0;
}

.hero-photo img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid rgba(255,255,255,0.2);
    box-shadow: 0 8px 32px rgba(0,0,0,0.3);
}

.hero-content {
    color: #FFFFFF;
}

.hero-name {
    font-size: 2.8rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin-bottom: 0.15em;
    line-height: 1.1;
}

.hero-title {
    font-size: 1.2rem;
    font-weight: 400;
    opacity: 0.9;
    margin-bottom: 0.3em;
    letter-spacing: 0.02em;
}

.hero-affiliation {
    font-size: 0.95rem;
    opacity: 0.7;
    margin-bottom: 1em;
}

.hero-tagline {
    font-size: 1.05rem;
    font-style: italic;
    opacity: 0.85;
    line-height: 1.6;
    max-width: 520px;
    margin-bottom: 0.8em;
}

.hero-email {
    font-size: 0.9rem;
    opacity: 0.7;
    margin-bottom: 1.5em;
}

.hero-email a {
    color: #FFFFFF;
    opacity: 0.9;
    border-bottom: 1px solid rgba(255,255,255,0.3);
}

.hero-email a:hover {
    opacity: 1;
    border-bottom-color: rgba(255,255,255,0.7);
}

.hero-buttons {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 1.2em;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 22px;
    border-radius: 6px;
    font-family: var(--font-body);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    border: none;
}

.btn-primary {
    background: #FFFFFF;
    color: #1B3A5C;
}

.btn-primary:hover {
    background: #E8EEF5;
    color: #1B3A5C;
    transform: translateY(-1px);
}

.btn-outline {
    background: transparent;
    color: #FFFFFF;
    border: 1.5px solid rgba(255,255,255,0.4);
}

.btn-outline:hover {
    background: rgba(255,255,255,0.1);
    border-color: rgba(255,255,255,0.7);
    color: #FFFFFF;
    transform: translateY(-1px);
}

.hero-links {
    display: flex;
    gap: 16px;
}

.hero-links a {
    color: rgba(255,255,255,0.6);
    font-size: 1.3rem;
    transition: color 0.3s ease, transform 0.3s ease;
}

.hero-links a:hover {
    color: #FFFFFF;
    transform: translateY(-2px);
}

/* ============================================
   ABOUT SECTION
   ============================================ */
#about {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-light);
}

.about-text p {
    color: var(--text-secondary);
    font-size: 1.05rem;
    margin-bottom: 1.2em;
    max-width: 780px;
}

.about-text a {
    color: var(--accent);
    border-bottom: 1px dashed var(--accent);
}

/* ============================================
   RESEARCH SECTION
   ============================================ */
#research {
    background: var(--bg-primary);
}

.research-overview {
    color: var(--text-secondary);
    font-size: 1.05rem;
    max-width: 780px;
    margin-bottom: 2.5em;
    line-height: 1.8;
}

.research-areas {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-bottom: 3em;
}

.research-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 28px 24px;
    transition: all 0.3s ease;
}

.research-card:hover {
    box-shadow: var(--card-hover-shadow);
    transform: translateY(-3px);
    border-color: var(--accent);
}

.research-card-icon {
    font-size: 1.8rem;
    color: var(--accent);
    margin-bottom: 12px;
}

.research-card h3 {
    font-size: 1.15rem;
    margin-bottom: 0.6em;
    color: var(--text-primary);
}

.research-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

.current-project {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-left: 4px solid var(--accent);
    border-radius: 0 10px 10px 0;
    padding: 28px 32px;
}

.current-project h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5em;
}

.current-project p {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: 0.8em;
}

.project-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-top: 1em;
    font-size: 0.9rem;
    color: var(--text-tertiary);
}

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

.project-meta strong {
    color: var(--text-secondary);
}

/* ============================================
   PUBLICATIONS SECTION
   ============================================ */
#publications {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.pub-category {
    margin-bottom: 2.5em;
}

.pub-category h3 {
    font-size: 1.2rem;
    margin-bottom: 1em;
    color: var(--text-primary);
    font-family: var(--font-body);
    font-weight: 600;
}

.pub-item {
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px 24px;
    margin-bottom: 14px;
    transition: all 0.3s ease;
}

.pub-item:hover {
    box-shadow: var(--card-shadow);
}

.pub-citation {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 10px;
}

.pub-citation .pub-author-highlight {
    font-weight: 600;
    color: var(--text-primary);
}

.pub-bottom {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

.pub-badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.02em;
}

.pub-badge.published {
    background: var(--badge-published);
    color: var(--badge-published-text);
}

.pub-badge.review {
    background: var(--badge-review);
    color: var(--badge-review-text);
}

.pub-badge.conference {
    background: var(--badge-conference);
    color: var(--badge-conference-text);
}

.pub-link {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--accent);
    padding: 3px 10px;
    border: 1px solid var(--accent);
    border-radius: 4px;
    transition: all 0.3s ease;
}

.pub-link:hover {
    background: var(--accent);
    color: #FFFFFF;
}

/* ============================================
   COLLABORATION SECTION
   ============================================ */
#collaboration {
    background: var(--bg-primary);
}

.collab-statement {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 700px;
    margin-bottom: 2em;
    line-height: 1.8;
}

.collab-areas {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 2em;
}

.collab-area-tag {
    background: var(--accent-lighter);
    color: var(--accent);
    padding: 8px 18px;
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid var(--border);
}

.collab-people {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px;
    margin-bottom: 2em;
}

.collab-people h3 {
    font-size: 1.1rem;
    margin-bottom: 0.8em;
}

.collab-people p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.btn-accent {
    background: var(--accent);
    color: #FFFFFF;
    padding: 12px 28px;
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.95rem;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
}

.btn-accent:hover {
    background: var(--accent-light);
    color: #FFFFFF;
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(27, 58, 92, 0.3);
}

/* ============================================
   PROJECTS SECTION
   ============================================ */
#projects {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.project-card {
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    transition: all 0.3s ease;
}

.project-card:hover {
    box-shadow: var(--card-hover-shadow);
    transform: translateY(-3px);
}

.project-card.portfolio-card {
    grid-column: 1 / -1;
    background: var(--accent-lighter);
    border-color: var(--accent);
}

.project-thumb {
    width: 100%;
    height: 180px;
    background: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-tertiary);
    font-size: 3rem;
    border-bottom: 1px solid var(--border);
}

.project-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.project-info {
    padding: 22px 24px;
}

.project-info h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5em;
    color: var(--text-primary);
}

.project-info p {
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.6;
    margin-bottom: 1em;
}

.project-links {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.project-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent);
    padding: 5px 12px;
    border: 1px solid var(--border);
    border-radius: 5px;
    transition: all 0.3s ease;
}

.project-link:hover {
    background: var(--accent);
    color: #FFFFFF;
    border-color: var(--accent);
}

.portfolio-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    padding: 22px 24px;
}

.portfolio-links a {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    background: var(--bg-secondary);
    color: var(--accent);
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

.portfolio-links a:hover {
    background: var(--accent);
    color: #FFFFFF;
    border-color: var(--accent);
}

.project-card.placeholder-card {
    border-style: dashed;
    opacity: 0.5;
}

.project-card.placeholder-card .project-thumb {
    background: var(--bg-tertiary);
}

/* ============================================
   EDUCATION SECTION
   ============================================ */
#education {
    background: var(--bg-primary);
}

.edu-group {
    display: flex;
    gap: 28px;
    margin-bottom: 2.5em;
    align-items: flex-start;
}

.edu-logo {
    flex-shrink: 0;
    width: 80px;
    height: 80px;
    border-radius: 12px;
    object-fit: contain;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 8px;
}

.edu-degrees {
    flex: 1;
}

.edu-uni-name {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 0.8em;
    color: var(--text-primary);
}

.edu-entry {
    padding: 12px 0;
    border-bottom: 1px solid var(--border-light);
}

.edu-entry:last-child {
    border-bottom: none;
}

.edu-degree {
    font-weight: 600;
    font-size: 1rem;
    color: var(--text-primary);
}

.edu-timeline {
    font-size: 0.88rem;
    color: var(--text-tertiary);
    margin-top: 2px;
}

.edu-awards-tag {
    display: inline-block;
    margin-top: 6px;
    padding: 2px 10px;
    font-size: 0.78rem;
    font-weight: 600;
    background: var(--badge-published);
    color: var(--badge-published-text);
    border-radius: 4px;
}

.awards-section {
    margin-top: 2em;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px;
}

.awards-section h3 {
    font-size: 1.15rem;
    margin-bottom: 0.8em;
    display: flex;
    align-items: center;
    gap: 8px;
}

.award-item {
    color: var(--text-secondary);
    font-size: 0.95rem;
    padding: 6px 0;
    border-bottom: 1px dashed var(--border-light);
}

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

/* ============================================
   SKILLS SECTION
   ============================================ */
#skills {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
    border-bottom: 1px solid var(--border-light);
}

.skills-category {
    margin-bottom: 2em;
}

.skills-category h3 {
    font-family: var(--font-body);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1em;
}

.skills-group {
    margin-bottom: 1.2em;
}

.skills-group-label {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 8px;
}

.tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.tag {
    display: inline-block;
    padding: 5px 14px;
    background: var(--tag-bg);
    color: var(--tag-text);
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    transition: all 0.3s ease;
    border: 1px solid transparent;
}

.tag:hover {
    border-color: var(--accent);
    transform: translateY(-1px);
}

.soft-skills-tags {
    margin-top: 1em;
}

.soft-skills-tags .tag {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
}

/* ============================================
   CONTACT SECTION
   ============================================ */
#contact {
    background: var(--bg-primary);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.contact-info h3 {
    font-size: 1.15rem;
    margin-bottom: 1em;
}

.contact-email {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: 1.5em;
}

.contact-email i {
    color: var(--accent);
    font-size: 1.2rem;
}

.contact-socials {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.contact-socials a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

.contact-socials a:hover {
    background: var(--accent);
    color: #FFFFFF;
    border-color: var(--accent);
    transform: translateY(-2px);
}

.contact-form h3 {
    font-size: 1.15rem;
    margin-bottom: 1em;
}

.form-group {
    margin-bottom: 14px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-family: var(--font-body);
    font-size: 0.92rem;
    color: var(--text-primary);
    background: var(--bg-secondary);
    transition: border-color 0.3s ease;
    outline: none;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--accent);
}

.form-group textarea {
    resize: vertical;
    min-height: 110px;
}

.form-submit {
    background: var(--accent);
    color: #FFFFFF;
    border: none;
    padding: 11px 28px;
    border-radius: 6px;
    font-family: var(--font-body);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.form-submit:hover {
    background: var(--accent-light);
    transform: translateY(-1px);
}

/* ============================================
   FOOTER
   ============================================ */
footer {
    background: var(--footer-bg);
    color: rgba(255,255,255,0.7);
    padding: 40px 0 24px;
}

.footer-inner {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
    text-align: center;
}

.footer-socials {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-bottom: 1.2em;
}

.footer-socials a {
    color: rgba(255,255,255,0.5);
    font-size: 1.2rem;
    transition: color 0.3s ease, transform 0.3s ease;
}

.footer-socials a:hover {
    color: #FFFFFF;
    transform: translateY(-2px);
}

.footer-text {
    font-size: 0.85rem;
    line-height: 1.8;
}

.footer-text a {
    color: rgba(255,255,255,0.8);
}

.footer-heart {
    color: #e74c3c;
}

.back-to-top {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: rgba(255,255,255,0.5);
    font-size: 0.85rem;
    margin-top: 1em;
    transition: color 0.3s ease;
}

.back-to-top:hover {
    color: #FFFFFF;
}

/* ============================================
   VISITOR COUNTER (floating badge)
   ============================================ */
.visitor-badge {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 999;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 30px;
    padding: 6px 16px;
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.1);
    font-size: 0.8rem;
    color: var(--text-secondary);
    transition: all 0.3s ease;
}

.visitor-badge i {
    color: var(--accent);
}

.visitor-badge img {
    height: 18px;
}

/* ============================================
   ANIMATIONS
   ============================================ */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 900px) {
    .research-areas {
        grid-template-columns: 1fr;
    }

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

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

@media (max-width: 768px) {
    .hero-inner {
        flex-direction: column;
        text-align: center;
        gap: 30px;
        padding-top: 20px;
    }

    .hero-name {
        font-size: 2rem;
    }

    .hero-tagline {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-links {
        justify-content: center;
    }

    .nav-links {
        display: none;
        position: fixed;
        top: 64px;
        left: 0;
        width: 100%;
        background: var(--bg-secondary);
        flex-direction: column;
        padding: 20px 24px;
        gap: 0;
        border-bottom: 1px solid var(--border);
        box-shadow: 0 8px 20px rgba(0,0,0,0.1);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links a {
        padding: 12px 0;
        border-bottom: 1px solid var(--border-light);
        width: 100%;
    }

    .hamburger {
        display: block;
    }

    .edu-group {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    section {
        padding: 50px 0;
    }

    .section-title::after {
        left: 50%;
        transform: translateX(-50%);
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 120px 0 50px;
    }

    .hero-photo img {
        width: 150px;
        height: 150px;
    }

    .project-meta {
        flex-direction: column;
        gap: 8px;
    }
}