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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #ffffff;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: #2563eb;
    text-decoration: none;
}

.nav-menu {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: #333;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: #2563eb;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background-color: #333;
    margin: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.3);
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    position: relative;
    z-index: 2;
}

.hero-content {
    max-width: 600px;
    text-align: center;
}

.hero-profile {
    margin-bottom: 2rem;
}

.profile-photo {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: contain;
    object-position: center;
    border: 4px solid #fff;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
    opacity: 0;
    animation: fadeInPhoto 1s ease forwards;
    animation-delay: 0.5s;
    background: #f8f9fa;
}

@keyframes fadeInPhoto {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.profile-photo:hover {
    transform: scale(1.05);
    border-color: #fbbf24;
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.4);
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.highlight {
    color: #fbbf24;
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: #e5e7eb;
}

h4.hero-subtitle {
    font-size: 1.25rem;
    font-weight: 400;
    color: #d1d5db;
    margin-bottom: 1.5rem;
}

.hero-location-small {
    font-size: 0.9rem;
    color: #fff;
    margin: 0.5rem 0 1.5rem 0;
    font-weight: 300;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.hero-description {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    color: #d1d5db;
    line-height: 1.6;
}

.hero-location {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 2rem;
    font-size: 1.1rem;
    color: #e5e7eb;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    margin-bottom: 3rem;
    justify-content: center;
}

.btn {
    padding: 12px 30px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn-primary {
    background-color: #fbbf24;
    color: #1f2937;
}

.btn-primary:hover {
    background-color: #f59e0b;
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: #3b82f6;
    color: white;
    border: 2px solid #3b82f6;
}

html {
  scroll-behavior: smooth;
}

.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.5);
  color: #2563eb;
  border-radius: 50%;
  border: 1px solid rgba(37, 99, 235, 0.25);
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
  text-decoration: none;
  z-index: 999;
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: opacity 0.25s ease, transform 0.25s ease, background 0.2s ease;
}

.back-to-top:hover {
  background: rgba(255, 255, 255, 0.75);
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.skill-item.secondary {
  opacity: 0.7;
}

.btn-secondary:hover {
    background-color: #2563eb;
    border-color: #2563eb;
    transform: translateY(-2px);
}

.hero-social {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.social-link {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.2rem;
    text-decoration: none;
    transition: all 0.3s ease;
}

.social-link:hover {
    background-color: #fbbf24;
    color: #1f2937;
    transform: translateY(-3px);
}

/* Section Styles */
section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: #1f2937;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background-color: #2563eb;
    border-radius: 2px;
}

/* About Section */
.about {
    background-color: #f9fafb;
}

.about-intro {
    font-size: 1.2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: #4b5563;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.about-highlights {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.5rem;
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.highlight-item i {
    font-size: 2rem;
    color: #2563eb;
    margin-top: 0.5rem;
}

.highlight-item h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1f2937;
}

.highlight-item p {
    color: #6b7280;
}

.about-mission {
    font-size: 1.1rem;
    text-align: center;
    color: #4b5563;
    max-width: 700px;
    margin: 0 auto;
}

/* Skills Section */
.skills-content {
    display: grid;
    gap: 3rem;
}

.skills-category {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.category-title {
    display: flex;
    align-items: center;
    gap: 1rem;
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: #1f2937;
}

.category-title i {
    color: #2563eb;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    justify-items: center;
}

.skill-item {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem;
    border-radius: 10px;
    text-align: center;
    font-weight: 500;
    transition: transform 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 60px;
    width: 100%;
}

.skill-item:hover {
    transform: translateY(-3px);
}

/* Projects Section */
.projects {
    background-color: #f9fafb;
}

.projects-content {
    display: grid;
    gap: 4rem;
}

.project-category {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.project-card {
    background: #f8fafc;
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid #e5e7eb;
    transition: all 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.1);
}

.project-card.placeholder {
    border: 2px dashed #d1d5db;
    background: #f9fafb;
}

.project-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.project-header i {
    font-size: 1.5rem;
    color: #2563eb;
}

.project-header h4 {
    font-size: 1.3rem;
    font-weight: 600;
    color: #1f2937;
}

.project-card p {
    color: #6b7280;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tag {
    background: #dbeafe;
    color: #1e40af;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

.project-links {
    display: flex;
    gap: 1rem;
}

.project-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: #2563eb;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.project-link:hover {
    color: #1d4ed8;
}

.project-status {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: #6b7280;
    font-style: italic;
}

/* Experience Section */
.experience-content {
    max-width: 900px;
    margin: 0 auto;
    display: grid;
    gap: 2rem;
}

.experience-item {
    display: flex;
    gap: 2rem;
    padding: 2rem;
    background: #f8fafc;
    border-radius: 15px;
    border: 1px solid #e5e7eb;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    position: relative;
    overflow: hidden;
}

.experience-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(to bottom, #2563eb, #7c3aed);
}

.experience-item.current::before {
    background: linear-gradient(to bottom, #059669, #10b981);
}

.experience-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: rgba(37, 99, 235, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #2563eb;
    font-size: 1.5rem;
}

.experience-item.current .experience-icon {
    background: rgba(5, 150, 105, 0.12);
    color: #059669;
}

.experience-details {
    flex: 1;
}

.experience-details h3 {
    font-size: 1.4rem;
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 0.5rem;
}

.experience-company {
    font-size: 1.1rem;
    color: #4b5563;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.experience-company-link {
    color: #2563eb;
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.experience-company-link:hover {
    color: #1d4ed8;
    text-decoration: underline;
}

.experience-type {
    color: #6b7280;
    font-size: 1rem;
}

.experience-date,
.experience-location {
    color: #6b7280;
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.experience-description {
    color: #4b5563;
    line-height: 1.6;
    margin: 1rem 0 1.25rem 0;
}

.experience-skills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

/* Papers Section */
.papers {
    background-color: #f9fafb;
}

.papers-content {
    max-width: 900px;
    margin: 0 auto;
}

.paper-item {
    display: flex;
    gap: 2rem;
    padding: 2rem;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.paper-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: rgba(37, 99, 235, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #2563eb;
    font-size: 1.5rem;
}

.paper-details {
    flex: 1;
}

.paper-details h3 {
    font-size: 1.4rem;
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.paper-meta {
    font-size: 1rem;
    color: #4b5563;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.paper-description {
    color: #4b5563;
    line-height: 1.6;
    margin-bottom: 1.25rem;
}

.paper-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.25rem;
}

.paper-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: #2563eb;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.paper-link:hover {
    color: #1d4ed8;
}

/* Education Section */
.education-content {
    max-width: 800px;
    margin: 0 auto;
}

.education-item {
    display: flex;
    gap: 2rem;
    margin-bottom: 3rem;
    padding: 2rem;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.education-item.current {
    border-left: 4px solid #2563eb;
}

.education-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
}

.education-details h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 0.5rem;
}

.education-details h4 {
    font-size: 1.2rem;
    color: #2563eb;
    margin-bottom: 0.5rem;
}

.education-location {
    color: #6b7280;
    margin-bottom: 0.5rem;
}

.education-status {
    color: #059669;
    font-weight: 500;
    margin-bottom: 1rem;
}

.education-description {
    color: #4b5563;
    line-height: 1.6;
}

/* Certifications Section */
.certifications {
    background-color: #f9fafb;
}

.certifications-content {
    max-width: 800px;
    margin: 0 auto;
}

.certification-item {
    display: flex;
    gap: 2rem;
    margin-bottom: 2rem;
    padding: 2rem;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
    position: relative;
    overflow: hidden;
}

.certification-item:hover {
    transform: translateY(-5px);
}

.certification-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(to bottom, #2563eb, #7c3aed);
}

.certification-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: rgba(37, 99, 235, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #2563eb;
    font-size: 1.5rem;
}

.certification-details {
    flex: 1;
}

.certification-details h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: #1f2937;
    margin-bottom: 0.3rem;
    line-height: 1.4;
}

.certification-issuer {
    font-size: 1.1rem;
    color: #4b5563;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.certification-date {
    color: #6b7280;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.certification-skills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.cert-tag {
    background: #eff6ff;
    color: #2563eb;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid #dbeafe;
}

.certification-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: #2563eb;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.certification-link:hover {
    color: #1d4ed8;
}

/* CV Section */
.cv {
    background-color: #ffffff;
}

.cv-content {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

.cv-description {
    font-size: 1.2rem;
    color: #4b5563;
    margin-bottom: 2rem;
}

.cv-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.cv-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 12px 24px;
    font-size: 1rem;
}

.cv-btn i {
    font-size: 1.1rem;
}

.cv-viewer {
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    margin-top: 2rem;
}

.cv-iframe {
    width: 100%;
    height: 800px;
    border: none;
    display: block;
}

/* Contact Section */
.contact {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.contact .section-title {
    color: white;
}

.contact .section-title::after {
    background-color: #fbbf24;
}

.contact-text {
    text-align: center;
    font-size: 1.2rem;
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.contact-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 2rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    text-decoration: none;
    color: white;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.contact-link:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-5px);
}

.contact-link i {
    font-size: 2rem;
    color: #fbbf24;
}

.contact-link h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.3rem;
}

.contact-link p {
    color: #e5e7eb;
    font-size: 0.9rem;
}

/* Footer */
.footer {
    background-color: #1f2937;
    color: #9ca3af;
    text-align: center;
    padding: 2rem 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .profile-photo {
        width: 150px;
        height: 150px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .hero-social {
        justify-content: center;
    }
    
    .btn {
        text-align: center;
        min-width: 200px;
    }
    
    .about-highlights {
        grid-template-columns: 1fr;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .education-item, .certification-item, .experience-item, .paper-item {
        flex-direction: column;
        text-align: center;
    }

    .certification-issuer, .certification-date, .certification-skills, .certification-link, .experience-company, .experience-date, .experience-location, .experience-skills, .paper-meta, .paper-tags, .paper-link {
        justify-content: center;
    }
    
    .skills-grid {
        grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
        gap: 1rem;
        justify-items: center;
    }
    
    .skill-item {
        padding: 0.9rem;
        font-size: 0.95rem;
        min-height: 55px;
    }
    
    .contact-links {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .profile-photo {
        width: 120px;
        height: 120px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }
    
    .hero-social {
        justify-content: center;
    }
    
    .skills-grid {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
        gap: 0.8rem;
        justify-items: center;
    }
    
    .skill-item {
        padding: 0.8rem;
        font-size: 0.9rem;
        min-height: 50px;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .container {
        padding: 0 15px;
    }
    
    section {
        padding: 60px 0;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-content > * {
    animation: fadeInUp 0.8s ease-out forwards;
}

.hero-title {
    animation-delay: 0.2s;
}

.hero-subtitle {
    animation-delay: 0.4s;
}

.hero-description {
    animation-delay: 0.6s;
}

.hero-location {
    animation-delay: 0.8s;
}

.hero-buttons {
    animation-delay: 1s;
}

.hero-social {
    animation-delay: 1.2s;
}