/* Modern CSS - Clean slate design */

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

:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-bg: #ffffff;
  --color-bg-alt: #f9fafb;
  --color-border: #e5e7eb;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', monospace;
  --max-width: 1100px;
  --nav-height: 64px;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--color-primary-dark);
}

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

/* Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid transparent;
  z-index: 100;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.nav.scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-weight: 600;
  font-size: 1.125rem;
  color: var(--color-text);
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  color: var(--color-text-light);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--color-text);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  width: 24px;
  height: 2px;
  background: var(--color-text);
  transition: transform 0.3s, opacity 0.3s;
}

.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 Section */
.hero {
  padding: calc(var(--nav-height) + 80px) 0 80px;
  min-height: 100vh;
  display: flex;
  align-items: center;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 60px;
  align-items: center;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-text-light);
  margin-bottom: 24px;
}

.hero-subtitle a {
  color: var(--color-primary);
  font-weight: 500;
}

.hero-description {
  font-size: 1.1rem;
  color: var(--color-text-light);
  margin-bottom: 16px;
  line-height: 1.7;
}

.hero-links {
  display: flex;
  gap: 12px;
  margin-top: 32px;
  flex-wrap: wrap;
}

.hero-image img {
  width: 100%;
  border-radius: 12px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: 8px;
  font-weight: 500;
  font-size: 0.95rem;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  color: white;
}

.btn-secondary {
  background: var(--color-bg-alt);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: var(--color-border);
  color: var(--color-text);
}

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

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 48px;
  letter-spacing: -0.02em;
}

/* Research Cards */
.research {
  background: var(--color-bg-alt);
}

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

.research-card {
  background: white;
  padding: 32px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
  transition: box-shadow 0.3s, transform 0.3s;
}

.research-card:hover {
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
  transform: translateY(-2px);
}

.research-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--color-primary), #3b82f6);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.research-icon i {
  color: white;
  font-size: 1.25rem;
}

.research-card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.research-card .venue {
  font-size: 0.85rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: 12px;
}

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

.research-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 16px;
  font-weight: 500;
  font-size: 0.9rem;
}

.research-link i {
  font-size: 0.75rem;
  transition: transform 0.2s;
}

.research-link:hover i {
  transform: translateX(3px);
}

/* Timeline */
.timeline {
  position: relative;
  padding-left: 32px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  padding-bottom: 40px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-marker {
  position: absolute;
  left: -32px;
  top: 6px;
  width: 16px;
  height: 16px;
  background: white;
  border: 3px solid var(--color-primary);
  border-radius: 50%;
}

.timeline-content {
  background: var(--color-bg-alt);
  padding: 24px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
}

.timeline-header {
  margin-bottom: 12px;
}

.timeline-header h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.timeline-company {
  color: var(--color-primary);
  font-weight: 500;
  font-size: 0.95rem;
}

.timeline-date {
  color: var(--color-text-light);
  font-size: 0.85rem;
  margin-left: 12px;
}

.timeline-content > p {
  color: var(--color-text-light);
  font-size: 0.95rem;
  line-height: 1.6;
}

.timeline-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.timeline-tags span {
  background: white;
  color: var(--color-text-light);
  font-size: 0.8rem;
  padding: 4px 12px;
  border-radius: 100px;
  border: 1px solid var(--color-border);
}

/* Service Grid */
.service {
  background: var(--color-bg-alt);
}

.service-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.service-item {
  background: white;
  padding: 24px;
  border-radius: 12px;
  border: 1px solid var(--color-border);
  text-align: center;
}

.service-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.service-item p {
  color: var(--color-text-light);
  font-size: 0.9rem;
}

/* Talks */
.talks-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.talk-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 24px;
  background: var(--color-bg-alt);
  border-radius: 8px;
  border: 1px solid var(--color-border);
}

.talk-title {
  font-weight: 500;
  color: var(--color-text);
}

.talk-venue {
  color: var(--color-text-light);
  font-size: 0.9rem;
}

/* Contact */
.contact {
  background: var(--color-bg-alt);
  text-align: center;
}

.contact-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}

.contact-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px 24px;
  background: white;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  font-weight: 500;
  transition: all 0.2s;
}

.contact-link:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.contact-link i {
  font-size: 1.25rem;
}

/* Footer */
.footer {
  padding: 32px 0;
  text-align: center;
  border-top: 1px solid var(--color-border);
}

.footer p {
  color: var(--color-text-light);
  font-size: 0.9rem;
}

/* Publications Page */
.page-header {
  padding: calc(var(--nav-height) + 60px) 0 40px;
  text-align: center;
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.page-header p {
  color: var(--color-text-light);
  font-size: 1.1rem;
}

.publications-section {
  padding: 40px 0 80px;
}

.year-heading {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-primary);
  margin: 48px 0 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-border);
}

.year-heading:first-child {
  margin-top: 0;
}

.pub-list {
  list-style: none;
}

.pub-item {
  padding: 24px;
  margin-bottom: 16px;
  background: var(--color-bg-alt);
  border-radius: 12px;
  border: 1px solid var(--color-border);
  transition: box-shadow 0.2s;
}

.pub-item:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.pub-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.pub-authors {
  color: var(--color-text-light);
  font-size: 0.95rem;
  margin-bottom: 8px;
}

.pub-authors em {
  color: var(--color-text);
  font-style: normal;
  font-weight: 500;
}

.pub-venue {
  color: var(--color-primary);
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 12px;
}

.pub-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.pub-links a {
  font-size: 0.85rem;
  padding: 6px 12px;
  background: white;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  color: var(--color-text-light);
  transition: all 0.2s;
}

.pub-links a:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.pub-abstract {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-light);
  font-size: 0.9rem;
  line-height: 1.7;
  display: none;
}

.pub-abstract.open {
  display: block;
}

/* Responsive */
@media (max-width: 900px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-image {
    order: -1;
    max-width: 250px;
    margin: 0 auto;
  }

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

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

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

@media (max-width: 768px) {
  .nav-links {
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: 24px;
    gap: 16px;
    border-bottom: 1px solid var(--color-border);
    display: none;
  }

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

  .nav-toggle {
    display: flex;
  }

  .hero h1 {
    font-size: 2.25rem;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .talk-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .contact-links {
    flex-direction: column;
    align-items: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  section {
    padding: 60px 0;
  }

  .hero {
    padding: calc(var(--nav-height) + 40px) 0 60px;
    min-height: auto;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .btn {
    padding: 10px 16px;
    font-size: 0.9rem;
  }

  .research-card {
    padding: 24px;
  }

  .timeline {
    padding-left: 24px;
  }

  .timeline-marker {
    left: -24px;
    width: 12px;
    height: 12px;
  }

  .timeline::before {
    left: 5px;
  }
}