:root {
  --ieee-blue: #006699;
  --ieee-navy: #003366;
  --ieee-gold: #FFCC33;
  --bg-light: #F8F9FA;
  --white: #FFFFFF;
  --gray-50: #F9FAFB;
  --gray-100: #F3F4F6;
  --gray-200: #E5E7EB;
  --gray-300: #D1D5DB;
  --gray-500: #6B7280;
  --gray-700: #374151;
  --gray-900: #111827;
  --accent-blue: #E6F2F8;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--white);
  color: var(--gray-700);
  line-height: 1.6;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6, .nav-logo {
  font-family: 'Space Grotesk', sans-serif;
  color: var(--ieee-navy);
  font-weight: 700;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Navigation */
#main-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--white);
  border-bottom: 3px solid var(--ieee-blue);
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  transition: var(--transition);
}

.nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 80px;
}

.nav-logo {
  font-size: 1.5rem;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-logo span {
  color: var(--ieee-blue);
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--gray-700);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  transition: var(--transition);
}

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

.nav-cta {
  background: var(--ieee-blue);
  color: var(--white) !important;
  padding: 0.6rem 1.2rem;
  border-radius: 4px;
}

.nav-cta:hover {
  background: var(--ieee-navy);
}

/* Mobile Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  display: block;
  width: 25px;
  height: 2px;
  background: var(--ieee-navy);
  margin: 5px 0;
  transition: var(--transition);
}

/* Hero Section */
#hero {
  padding-top: 80px;
  min-height: 80vh;
  display: flex;
  align-items: center;
  background: linear-gradient(rgba(0, 51, 102, 0.85), rgba(0, 102, 153, 0.85)), url('https://images.unsplash.com/photo-1451187580459-43490279c0fa?auto=format&fit=crop&q=80&w=2000') center/cover;
  color: var(--white);
  text-align: center;
}

.hero-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

.hero-badge {
  background: var(--ieee-gold);
  color: var(--ieee-navy);
  display: inline-block;
  padding: 0.4rem 1rem;
  font-weight: 700;
  font-size: 0.8rem;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
  border-radius: 2px;
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  color: var(--white);
  margin-bottom: 1rem;
  line-height: 1.1;
}

.hero-subtitle {
  font-size: 1.5rem;
  margin-bottom: 2.5rem;
  font-weight: 300;
  opacity: 0.9;
}

.hero-info-bar {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 3rem;
  flex-wrap: wrap;
}

.info-chip {
  background: rgba(255,255,255,0.1);
  padding: 1rem 1.5rem;
  border-radius: 4px;
  border: 1px solid rgba(255,255,255,0.2);
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.chip-value {
  font-weight: 700;
}

.hero-cta-group {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
}

.hero-btn {
  padding: 0.8rem 2rem;
  border-radius: 4px;
  text-decoration: none;
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.9rem;
  transition: var(--transition);
}

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

.hero-btn.secondary {
  background: transparent;
  color: var(--white);
  border: 2px solid var(--white);
}

.hero-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

/* Section Styles */
.section {
  padding: 5rem 0;
}

.section-bg {
  background: var(--bg-light);
}

.section-header {
  text-align: center;
  margin-bottom: 3.5rem;
}

.section-tag {
  color: var(--ieee-blue);
  text-transform: uppercase;
  font-weight: 700;
  letter-spacing: 2px;
  font-size: 0.8rem;
  display: block;
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: 2.5rem;
  position: relative;
  padding-bottom: 1rem;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--ieee-blue);
}

/* About Grid */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.objective-card {
  background: var(--white);
  padding: 2.5rem;
  border-left: 5px solid var(--ieee-blue);
  box-shadow: 0 4px 20px rgba(0,0,0,0.05);
}

.highlight-item {
  display: flex;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.highlight-icon {
  font-size: 1.5rem;
  background: var(--accent-blue);
  color: var(--ieee-blue);
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
  flex-shrink: 0;
}

/* Tracks */
.tracks-nav {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.track-tab {
  background: var(--white);
  border: 1px solid var(--gray-200);
  padding: 0.75rem 1.5rem;
  cursor: pointer;
  font-weight: 600;
  transition: var(--transition);
  border-radius: 4px;
}

.track-tab.active, .track-tab:hover {
  background: var(--ieee-blue);
  color: var(--white);
  border-color: var(--ieee-blue);
}

.track-panel {
  display: none;
  background: var(--white);
  padding: 2.5rem;
  border: 1px solid var(--gray-200);
  border-radius: 4px;
}

.track-panel.active {
  display: block;
}

.track-header {
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.track-number {
  font-size: 3rem;
  color: var(--accent-blue);
  font-weight: 800;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}

.topic-item {
  background: var(--gray-50);
  padding: 1rem;
  border-radius: 4px;
  font-size: 0.9rem;
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  border: 1px solid transparent;
  transition: var(--transition);
}

.topic-item:hover {
  border-color: var(--ieee-blue);
  background: var(--white);
}

.topic-dot {
  color: var(--ieee-blue);
  font-weight: bold;
}

/* Timeline/Dates */
.dates-pub-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
}

.timeline {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.timeline-item {
  display: flex;
  justify-content: space-between;
  padding: 1rem;
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: 4px;
}

.timeline-item.highlight {
  border-left: 4px solid var(--ieee-blue);
  background: var(--accent-blue);
}

.timeline-label {
  font-weight: 700;
  color: var(--ieee-navy);
}

.timeline-date {
  font-weight: 600;
  color: var(--ieee-blue);
}

/* Cards */
.pub-card, .fee-card, .guidelines-card {
  background: var(--white);
  padding: 2rem;
  border: 1px solid var(--gray-200);
  margin-bottom: 1.5rem;
  border-radius: 4px;
}

.pub-card h3, .fee-card h3, .guidelines-card h3 {
  border-bottom: 2px solid var(--accent-blue);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
}

.index-badges {
  display: flex;
  gap: 0.5rem;
  margin-top: 1rem;
}

.index-badge {
  background: var(--ieee-navy);
  color: var(--white);
  padding: 0.25rem 0.75rem;
  font-size: 0.75rem;
  border-radius: 2px;
  font-weight: 600;
}

/* Fees Table Style */
.fee-list {
  list-style: none;
}

.fee-list li {
  display: flex;
  justify-content: space-between;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--gray-100);
}

.fee-list li strong {
  color: var(--ieee-blue);
}

/* Footer */
footer {
  background: var(--ieee-navy);
  color: var(--white);
  padding: 4rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand h3 {
  color: var(--white);
  margin-bottom: 1rem;
}

.footer-links-col h4 {
  color: var(--ieee-gold);
  margin-bottom: 1.5rem;
  text-transform: uppercase;
  font-size: 0.9rem;
}

.footer-links-col ul {
  list-style: none;
}

.footer-links-col li {
  margin-bottom: 0.5rem;
}

.footer-links-col a {
  color: rgba(255,255,255,0.7);
  text-decoration: none;
  font-size: 0.9rem;
}

.footer-links-col a:hover {
  color: var(--white);
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 2rem;
  text-align: center;
  font-size: 0.8rem;
  opacity: 0.7;
}

/* Animations */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.6s ease-out;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 992px) {
  .about-grid, .dates-pub-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 80px;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: 2rem;
    box-shadow: 0 10px 10px rgba(0,0,0,0.1);
  }
  
  .nav-links.open {
    display: flex;
  }
  
  .nav-toggle {
    display: block;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
}