:root {
  --primary: #0a192f;
  --secondary: #112240;
  --accent: #64ffda;
  --text: #ccd6f6;
  --text-secondary: #8892b0;
  --white: #e6f1ff;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background-color: var(--primary);
  color: var(--text);
  line-height: 1.6;
}

header {
  padding: 20px 50px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: fixed;
  width: 100%;
  top: 0;
  background-color: rgba(10, 25, 47, 0.85);
  backdrop-filter: blur(10px);
  z-index: 1000;
  transition: all 0.3s ease;
}

header.scrolled {
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.3);
  padding: 12px 50px;
}

.logo {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent);
}

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

nav ul li a {
  margin-left: 30px;
  text-decoration: none;
  color: var(--text);
  font-weight: 500;
  font-size: 0.95rem;
  transition: all 0.3s ease;
  position: relative;
}

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

nav ul li a::after {
  content: "";
  position: absolute;
  width: 0;
  height: 2px;
  background-color: var(--accent);
  bottom: -5px;
  left: 0;
  transition: width 0.3s ease;
}

nav ul li a:hover::after {
  width: 100%;
}

.hero {
  height: 100vh;
  display: flex;
  align-items: center;
  padding: 0 150px;
  position: relative;
}

.hero-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.hero-text {
  max-width: 500px;
}

.hero-image {
  width: 400px;
  height: 400px;
  border-radius: 24px;
  overflow: hidden;
  box-shadow: 0 8px 30px rgba(100, 255, 218, 0.15);
}

.hero-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-content h1 {
  font-size: 3.5rem;
  margin-bottom: 10px;
  font-weight: 700;
}

.hero-content h2 {
  font-size: 2.5rem;
  margin-bottom: 20px;
  color: var(--text-secondary);
}

.hero-content p {
  font-size: 1.2rem;
  margin-bottom: 30px;
  color: var(--text-secondary);
  max-width: 600px;
}

.cta-btn {
  display: inline-block;
  padding: 12px 30px;
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 4px;
  text-decoration: none;
  font-weight: 500;
  margin-right: 15px;
  transition: all 0.3s ease;
}

.cta-btn:hover {
  background: rgba(100, 255, 218, 0.1);
  transform: translateY(-3px);
}

section {
  padding: 100px 150px;
}

.section-title {
  font-size: 2rem;
  margin-bottom: 20px;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: "";
  position: absolute;
  height: 1px;
  width: 300px;
  background-color: var(--text-secondary);
  top: 50%;
  margin-left: 20px;
}

.about-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.about-text {
  flex: 1;
  margin-right: 50px;
}

.about-text p {
  margin-bottom: 15px;
  color: var(--text-secondary);
}

.education-card {
  background-color: var(--secondary);
  border-radius: 8px;
  padding: 20px;
  margin-bottom: 20px;
  transition: transform 0.3s ease;
}

.education-card:hover {
  transform: translateY(-5px);
}

.education-card h3 {
  font-size: 1.2rem;
  margin-bottom: 10px;
}

.education-card p {
  color: var(--text-secondary);
  margin-bottom: 5px;
}

.education-card .score {
  color: var(--accent);
  font-weight: 500;
}

.experience-timeline {
  position: relative;
  max-width: 1200px;
  margin: 40px auto;
}

.experience-timeline::after {
  content: "";
  position: absolute;
  width: 2px;
  background-color: var(--text-secondary);
  top: 0;
  bottom: 0;
  left: 50%;
  margin-left: -1px;
}

.experience-container {
  padding: 10px 40px;
  position: relative;
  background-color: inherit;
  width: 50%;
}

.experience-container.left {
  left: 0;
}

.experience-container.right {
  left: 50%;
}

.experience-container::after {
  content: "";
  position: absolute;
  width: 20px;
  height: 20px;
  right: -10px;
  background-color: var(--accent);
  border-radius: 50%;
  top: 15px;
  z-index: 1;
}

.experience-container.right::after {
  left: -10px;
}

.experience-content {
  padding: 20px;
  background-color: var(--secondary);
  position: relative;
  border-radius: 8px;
}

.experience-content h3 {
  font-size: 1.2rem;
  margin-bottom: 5px;
}

.experience-content h4 {
  font-size: 1rem;
  color: var(--accent);
  margin-bottom: 10px;
}

.experience-content .date {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 15px;
}

.experience-content ul {
  list-style-type: none;
}

.experience-content ul li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
  color: var(--text-secondary);
}

.experience-content ul li::before {
  content: "▹";
  position: absolute;
  left: 0;
  color: var(--accent);
}

.project-grid,
.publications-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 25px;
  margin-top: 40px;
}

.project-card,
.publication-card {
  background-color: var(--secondary);
  border-radius: 8px;
  padding: 25px;
  transition: transform 0.3s ease;
  height: 100%;
  display: flex;
  flex-direction: column;
}

.project-card:hover,
.publication-card:hover {
  transform: translateY(-7px);
}

.project-card h3,
.publication-card h3 {
  font-size: 1.3rem;
  margin-bottom: 10px;
}

.project-card .project-date,
.publication-card .publication-date {
  font-size: 0.9rem;
  color: var(--accent);
  margin-bottom: 15px;
}

.project-card p,
.publication-card p {
  color: var(--text-secondary);
  margin-bottom: 15px;
  flex: 1;
}

.project-card .project-links,
.publication-card .publication-links {
  display: flex;
  gap: 15px;
  margin-top: auto;
}

.project-card .project-links a,
.publication-card .publication-links a {
  color: var(--text);
  text-decoration: none;
  font-size: 1.2rem;
  transition: color 0.3s ease;
}

.project-card .project-links a:hover,
.publication-card .publication-links a:hover {
  color: var(--accent);
}

.achievements-list {
  margin-top: 30px;
}

.achievement-item {
  background-color: var(--secondary);
  border-radius: 8px;
  padding: 20px;
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  transition: transform 0.3s ease;
}

.achievement-item:hover {
  transform: translateX(7px);
}

.achievement-icon {
  font-size: 1.5rem;
  color: var(--accent);
  margin-right: 20px;
}

.achievement-content h3 {
  font-size: 1.2rem;
  margin-bottom: 5px;
}

.achievement-content p {
  color: var(--text-secondary);
}

.skills-container {
  margin-top: 40px;
}

.skills-category {
  margin-bottom: 30px;
}

.skills-category h3 {
  font-size: 1.3rem;
  margin-bottom: 15px;
  color: var(--accent);
}

.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.skill-tag {
  background-color: var(--secondary);
  color: var(--text);
  padding: 8px 15px;
  border-radius: 50px;
  font-size: 0.9rem;
  transition: all 0.3s ease;
}

.skill-tag:hover {
  background-color: rgba(100, 255, 218, 0.1);
  color: var(--accent);
  transform: translateY(-3px);
}

.contact {
  text-align: center;
  max-width: 600px;
  margin: 0 auto;
}

.contact p {
  color: var(--text-secondary);
  margin-bottom: 30px;
}

.contact-links {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-top: 30px;
}

.contact-links a {
  color: var(--text);
  font-size: 1.8rem;
  transition: all 0.3s ease;
}

.contact-links a:hover {
  color: var(--accent);
  transform: translateY(-3px);
}

footer {
  text-align: center;
  padding: 30px 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.scroll-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 40px;
  height: 40px;
  background-color: var(--secondary);
  color: var(--accent);
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  font-size: 1.2rem;
  opacity: 0;
  transition: all 0.3s ease;
  z-index: 1000;
}

.scroll-top.visible {
  opacity: 1;
}

.scroll-top:hover {
  background-color: var(--accent);
  color: var(--primary);
}

/* PDF viewer modal */
.modal {
  display: none;
  position: fixed;
  z-index: 1100;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.7);
  overflow: auto;
}

.modal-content {
  background-color: var(--secondary);
  margin: 5% auto;
  padding: 20px;
  width: 90%;
  max-width: 900px;
  border-radius: 8px;
  position: relative;
  height: 85%;
}

.close-modal {
  position: absolute;
  right: 20px;
  top: 15px;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  transition: color 0.3s ease;
  z-index: 1200;
}

.close-modal:hover {
  color: var(--accent);
}

.pdf-container {
  width: 100%;
  height: 100%;
}

.pdf-container iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* Mobile responsiveness */
@media screen and (max-width: 1024px) {
  section,
  .hero {
    padding: 80px 80px;
  }

  header {
    padding: 15px 30px;
  }

  header.scrolled {
    padding: 10px 30px;
  }

  .hero-content h1 {
    font-size: 2.8rem;
  }

  .hero-content h2 {
    font-size: 2rem;
  }

  .section-title::after {
    width: 200px;
  }

  .hero-content {
    flex-direction: column-reverse;
    align-items: flex-start;
  }

  .hero-image {
    margin-bottom: 30px;
  }
}

@media screen and (max-width: 768px) {
  section {
    padding: 60px 40px;
  }

  .hero {
    height: auto;
    min-height: 100vh;
    padding: 120px 40px;
  }

  .hero-content h1 {
    font-size: 2.2rem;
  }

  .hero-content h2 {
    font-size: 1.8rem;
  }

  .hero-content p {
    font-size: 1rem;
  }

  .about-content {
    flex-direction: column;
  }

  .about-text {
    margin-right: 0;
    margin-bottom: 30px;
  }

  .experience-timeline::after {
    left: 31px;
  }

  .experience-container {
    width: 100%;
    padding-left: 70px;
    padding-right: 25px;
  }

  .experience-container.left,
  .experience-container.right {
    left: 0;
  }

  .experience-container.left::after,
  .experience-container.right::after {
    left: 21px;
  }

  .section-title::after {
    width: 100px;
  }

  .modal-content {
    width: 95%;
    margin-top: 10%;
  }
}

@media screen and (max-width: 480px) {
  header {
    padding: 15px 20px;
  }

  .logo {
    font-size: 1.5rem;
  }

  section,
  .hero {
    padding: 50px 20px;
  }

  .hero-content h1 {
    font-size: 1.8rem;
  }

  .hero-content h2 {
    font-size: 1.5rem;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .section-title::after {
    display: none;
  }

  .experience-container {
    padding-left: 60px;
    padding-right: 15px;
  }

  .hero-image {
    width: 150px;
    height: 150px;
  }

  nav {
    display: none; /* Mobile menu needs JavaScript, so hiding for now */
  }
}