/* TRIER Psychotherapy Congress 2025 - Main Stylesheet */
/* Color palette extracted from TPC logo */

:root {
  /* Primary Colors from TPC Logo */
  --tpc-purple-dark: #4A2B5C;
  --tpc-purple-medium: #6B2C91;
  --tpc-purple-light: #8E44AD;
  --tpc-yellow: #FFD700;
  --tpc-yellow-light: #FFF3CD;
  --tpc-orange: #FF6B35;
  --tpc-orange-light: #FFE5DB;
  
  /* Supporting Colors */
  --text-primary: #2C3E50;
  --text-secondary: #5D6D7E;
  --text-light: #7F8C8D;
  --white: #FFFFFF;
  --light-gray: #F8F9FA;
  --border-color: #E9ECEF;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, var(--tpc-purple-dark) 0%, var(--tpc-purple-medium) 50%, var(--tpc-orange) 100%);
  --gradient-secondary: linear-gradient(135deg, var(--tpc-yellow) 0%, var(--tpc-orange) 100%);
  --gradient-hero: linear-gradient(135deg, var(--tpc-purple-dark) 0%, var(--tpc-purple-medium) 100%);
  
  /* Typography */
  --font-primary: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --font-secondary: 'Arial', sans-serif;
  
  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-xxl: 4rem;
  
  /* Breakpoints */
  --mobile: 768px;
  --tablet: 1024px;
  --desktop: 1200px;
}

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

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

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  line-height: 1.3;
}

h1 {
  font-size: 2.5rem;
  color: var(--tpc-purple-dark);
}

h2 {
  font-size: 2rem;
  color: var(--tpc-purple-medium);
}

h3 {
  font-size: 1.5rem;
  color: var(--tpc-purple-medium);
}

p {
  margin-bottom: var(--spacing-sm);
  color: var(--text-secondary);
}

a {
  color: var(--tpc-purple-medium);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: var(--tpc-orange);
}

/* Header and Navigation */
.header {
  background: var(--white);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  transition: all 0.3s ease;
}

.header.scrolled {
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(10px);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.logo img {
  height: 85px;
  width: auto;
}

.logo-text {
  font-size: 1.8rem;
  font-weight: 600;
  color: var(--tpc-purple-dark);
}

.main-nav {
  display: flex;
  list-style: none;
  gap: var(--spacing-lg);
}

.main-nav li a {
  font-weight: 500;
  color: var(--text-primary);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: 5px;
  transition: all 0.3s ease;
}

.main-nav li a:hover,
.main-nav li a.active {
  background: var(--gradient-secondary);
  color: var(--white);
}

.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--tpc-purple-dark);
}

/* Hero Section */
.hero {
  background: var(--gradient-hero);
  color: var(--white);
  padding: 120px 0 var(--spacing-xxl);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 100" fill="rgba(255,255,255,0.1)"><polygon points="0,0 1000,100 1000,100 0,100"/></svg>') repeat-x;
  background-size: 100px 100px;
}

.hero-content {
  max-width: var(--desktop);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  position: relative;
  z-index: 1;
}

.hero h1 {
  color: var(--white);
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

.hero .subtitle {
  color: var(--white);
  font-size: 1.3rem;
  margin-bottom: var(--spacing-lg);
  opacity: 0.9;
}

.congress-info {
  display: flex;
  justify-content: center;
  gap: var(--spacing-xl);
  margin: var(--spacing-lg) 0;
  flex-wrap: wrap;
}

.info-item {
  text-align: center;
}

.info-item .icon {
  font-size: 2rem;
  margin-bottom: var(--spacing-xs);
  color: var(--tpc-yellow);
}

.info-item h3 {
  color: var(--white);
  font-size: 1.1rem;
  margin-bottom: var(--spacing-xs);
}

.info-item p {
  color: rgba(255,255,255,0.9);
  margin: 0;
}

/* Main Content */
.main-content {
  padding: var(--spacing-xxl) 0;
}

.container {
  max-width: var(--desktop);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.section {
  margin-bottom: var(--spacing-xxl);
}

.section-header {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.section-title {
  position: relative;
  display: inline-block;
  padding-bottom: var(--spacing-sm);
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--gradient-secondary);
  border-radius: 2px;
}

/* Cards */
.card {
  background: var(--white);
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  padding: var(--spacing-lg);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-lg);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-lg);
  background: var(--gradient-primary);
  color: var(--white);
  border: none;
  border-radius: 5px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
}

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

.btn-secondary {
  background: var(--white);
  color: var(--tpc-purple-medium);
  border: 2px solid var(--tpc-purple-medium);
}

.btn-secondary:hover {
  background: var(--tpc-purple-medium);
  color: var(--white);
}

/* Participant Cards */
.participant-card {
  text-align: center;
  padding: var(--spacing-lg);
}

.participant-photo {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  margin: 0 auto var(--spacing-sm);
  background: var(--gradient-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: var(--white);
  font-weight: bold;
}

.participant-name {
  color: var(--tpc-purple-dark);
  margin-bottom: var(--spacing-xs);
}

.participant-title {
  color: var(--tpc-orange);
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
}

.participant-institution {
  color: var(--text-secondary);
  font-style: italic;
  margin-bottom: var(--spacing-sm);
}

/* Keynote Speakers */
.keynote-speakers {
  background: var(--light-gray);
  padding: var(--spacing-xxl) 0;
  margin: var(--spacing-xxl) 0;
}

.keynote-card {
  background: var(--white);
  border-radius: 15px;
  padding: var(--spacing-xl);
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.keynote-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 5px;
  background: var(--gradient-secondary);
}

.keynote-photo {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  margin: 0 auto var(--spacing-md);
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: var(--white);
  font-weight: bold;
}

/* Expandable/Collapsible Sections */
.expandable {
  border-top: 1px solid var(--border-color);
  margin-top: 1rem;
}

.expandable-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 0 0.5rem 0;
  cursor: pointer;
  transition: color 0.3s ease;
  border: none;
  background: none;
  width: 100%;
  text-align: left;
}

.expandable-header:hover {
  color: var(--tpc-purple-medium);
}

.expandable-header h4 {
  margin: 0;
  color: var(--tpc-purple-medium);
  font-size: 1.1rem;
}

.expandable-arrow {
  font-size: 0.8rem;
  color: var(--tpc-orange);
  transition: transform 0.3s ease;
  font-weight: bold;
}

.expandable-arrow.expanded {
  transform: rotate(90deg);
}

.expandable-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out, padding 0.3s ease-out;
  padding: 0;
}

.expandable-content.expanded {
  max-height: 500px;
  padding-bottom: 1rem;
}

.expandable-content ul {
  margin-top: 0.5rem;
}

/* Footer */
.footer {
  background: var(--tpc-purple-dark);
  color: var(--white);
  padding: var(--spacing-xl) 0 var(--spacing-lg);
}

.footer-content {
  max-width: var(--desktop);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
}

.footer-section h3 {
  color: var(--tpc-yellow);
  margin-bottom: var(--spacing-sm);
}

.footer-section p,
.footer-section a {
  color: rgba(255,255,255,0.8);
  text-decoration: none;
}

.footer-section a:hover {
  color: var(--tpc-yellow);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-lg);
  border-top: 1px solid rgba(255,255,255,0.2);
  margin-top: var(--spacing-lg);
  color: rgba(255,255,255,0.6);
}

/* Responsive Design */
@media (max-width: 768px) {
  .main-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: var(--spacing-sm);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  }

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

  .mobile-menu-toggle {
    display: block;
  }

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

  .congress-info {
    flex-direction: column;
    gap: var(--spacing-md);
  }

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

  .nav-container {
    height: 70px;
  }

  .hero {
    padding: 100px 0 var(--spacing-xl);
  }
}

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

.fade-in-up {
  animation: fadeInUp 0.6s ease-out;
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.mt-lg { margin-top: var(--spacing-lg); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.py-xl { padding: var(--spacing-xl) 0; }