:root {
  --primary-color: #2563eb;
  --secondary-color: #1e40af;
  --accent-color: #3b82f6;
  --text-color: #1f2937;
  --light-text: #6b7280;
  --background-color: #ffffff;
  --section-bg: #f9fafb;
  --header-bg: #ffffff;
  --card-bg: #ffffff;
  --border-color: #e5e7eb;
  --max-width: 1200px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

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

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

/* Typography */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
  color: #111827;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; margin-top: 1rem; margin-bottom: 1rem; }
h3 { font-size: 1.5rem; margin-top: 0.75rem; color: #374151; }

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

a:hover {
  color: var(--secondary-color);
  text-decoration: underline;
}

/* Layout */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

/* Header / Hero */
header {
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
  padding: 3rem 0;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
}

.hero-title {
  font-size: 3.5rem;
  background: linear-gradient(to right, var(--secondary-color), var(--primary-color));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 1rem;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--light-text);
  margin-bottom: 1.5rem;
}

.hero-meta {
  display: flex;
  justify-content: center;
  gap: 2rem;
  font-weight: 500;
  color: #374151;
}

.hero-meta span {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Navigation */
nav {
  position: sticky;
  top: 0;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
  padding: 1rem 0;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

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

.nav-links a {
  font-weight: 600;
  color: #4b5563;
  padding: 0.5rem 1rem;
  border-radius: 0.375rem;
}

.nav-links a:hover {
  background-color: #f3f4f6;
  color: var(--primary-color);
  text-decoration: none;
}

/* Sections */
section {
  padding: 0.75rem 0;
}

section:nth-child(even) {
  background-color: var(--section-bg);
}

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

p {
  margin-bottom: 1rem;
}

/* Program Schedule */
.session {
  background-color: white;
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1rem;
  margin-bottom: 1rem;
  box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}

.session-header {
  border-bottom: 1px solid #f3f4f6;
  padding-bottom: 0.75rem;
  margin-bottom: 0.75rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: nowrap; /* Prevent wrapping so time stays on right */
  gap: 1rem;
}

.session-header h3 {
  margin: 0;
  flex: 1; /* Allow title to take flexible width */
  min-width: 0; /* Enable text wrapping inside flex item */
}

.session-header:last-child {
  border-bottom: none;
  padding-bottom: 0;
  margin-bottom: 0;
}


.session-time {
  background-color: #eff6ff;
  color: var(--primary-color);
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.875rem;
  font-weight: 600;
  white-space: nowrap; /* Keep time text together */
  flex-shrink: 0; /* Prevent time from shrinking */
}

.talk {
  margin-bottom: 1rem;
}

.talk:last-child {
  margin-bottom: 0;
}

.talk-title {
  font-weight: 600;
  font-size: 1.1rem;
  color: #111827;
  margin-bottom: 0.25rem;
}

.talk-authors {
  font-size: 0.95rem;
  color: #4b5563;
}

.talk-affiliation {
  font-size: 0.875rem;
  color: #6b7280;
  font-style: italic;
}

/* Organizers */
.organizer-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  text-align: center;
}

@media (min-width: 1024px) {
  .organizer-list {
    grid-template-columns: repeat(4, 1fr);
  }
}


.organizer-card {
  background-color: white;
  padding: 1rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.organizer-name {
  font-weight: 600;
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
  flex-grow: 1; /* Pushes the role to the bottom if name is short */
  display: flex;
  align-items: center; /* Centers name vertically in its available space if wanted, or use align-items: start on parent */
  justify-content: center;
}

.organizer-role {
  color: var(--light-text);
  font-size: 0.9rem;
  margin-top: auto; /* Ensures it stays at the bottom */
}

/* Footer */
footer {
  background-color: #1f2937;
  color: #f9fafb;
  padding: 2rem 0;
  text-align: center;
}

footer a {
  color: #60a5fa;
}

footer a:hover {
  color: #93c5fd;
}

/* Responsive */
@media (max-width: 768px) {
  .hero-title { font-size: 2.5rem; }
  .hero-meta { flex-direction: column; gap: 0.5rem; }
  .nav-links { gap: 1rem; font-size: 0.9rem; }
  .session-header { flex-direction: column; }
}

/* Dropdown Styles */
.nav-links li {
  position: relative;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: white;
  min-width: 160px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  border-radius: 0.5rem;
  padding: 0.5rem 0;
  z-index: 50;
  top: 100%;
  right: 0;
  margin-top: 0.5rem;
  text-align: left;
}

.dropdown-content a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--text-color);
  text-decoration: none;
  font-weight: 500;
  white-space: nowrap;
}

.dropdown-content a:hover {
  background-color: #f3f4f6;
  color: var(--primary-color);
}

.nav-links li:hover .dropdown-content {
  display: block;
}