:root {
  --primary-color: #2c5aa0;
  --secondary-color: #1a3d73;
  --accent-color: #f39c12;
  --text-dark: #2c3e50;
  --text-light: #ffffff;
  --text-muted: #7f8c8d;
  --bg-light: #ffffff;
  --bg-gray: #f8f9fa;
  --bg-dark: #2c3e50;
  --border-color: #e1e8ed;
  --shadow: 0 2px 15px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 5px 25px rgba(0, 0, 0, 0.15);
  --border-radius: 8px;
  --transition: all 0.3s ease;
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-dark);
  background-color: var(--bg-light);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header & Navigation */
.header {
  background: var(--bg-light);
  box-shadow: var(--shadow);
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
}

.navbar {
  padding: 1rem 0;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  height: 50px;
  width: auto;
}

.nav-menu {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-link {
  text-decoration: none;
  color: var(--text-dark);
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-link:hover {
  color: var(--primary-color);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary-color);
  transition: var(--transition);
}

.nav-link:hover::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
}

.bar {
  width: 25px;
  height: 3px;
  background: var(--text-dark);
  margin: 3px 0;
  transition: var(--transition);
}

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
  color: var(--text-light);
  padding: 120px 0 80px;
  text-align: center;
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('https://pixabay.com/get/gd092e49717641b613256eb679af859f97169974fab9d50dd7fa7ef16d5dd781bf00faeffd2362c3955a19fe74d48a66b712f2764452b16daeb1d396969f8cef9_1280.jpg') center/cover;
  opacity: 0.1;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
}

.hero-logo-img {
  max-width: 200px;
  height: auto;
  margin-bottom: 2rem;
  filter: brightness(0) invert(1);
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
  font-weight: 700;
}

.hero-date {
  font-size: 1.5rem;
  margin-bottom: 3rem;
  opacity: 0.9;
}

/* Countdown Timer */
.countdown-container {
  margin: 3rem 0;
}

.countdown {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.countdown-item {
  background: rgba(255, 255, 255, 0.1);
  padding: 2rem 1rem;
  border-radius: var(--border-radius);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.countdown-number {
  display: block;
  font-size: 3rem;
  font-weight: 700;
  color: var(--accent-color);
}

.countdown-label {
  font-size: 1rem;
  opacity: 0.8;
}

.countdown-message {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 2rem;
  background: var(--accent-color);
  color: var(--text-dark);
  padding: 1rem 2rem;
  border-radius: var(--border-radius);
  display: inline-block;
}

.cta-button {
  display: inline-block;
  background: var(--accent-color);
  color: var(--text-dark);
  padding: 1rem 3rem;
  text-decoration: none;
  border-radius: var(--border-radius);
  font-weight: 600;
  font-size: 1.2rem;
  transition: var(--transition);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.cta-button:hover {
  background: #e67e22;
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

/* Work Submission Section */
.work-submission {
  background: var(--bg-gray);
  padding: 5rem 0;
  text-align: center;
}

.work-submission h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.work-submission p {
  font-size: 1.1rem;
  margin-bottom: 3rem;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.work-actions {
  display: flex;
  gap: 2rem;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
}

.email-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--primary-color);
  text-decoration: none;
  font-size: 1.1rem;
  font-weight: 500;
  transition: var(--transition);
}

.email-link:hover {
  color: var(--secondary-color);
}

.submit-button {
  background: var(--primary-color);
  color: var(--text-light);
  padding: 1rem 2rem;
  text-decoration: none;
  border-radius: var(--border-radius);
  font-weight: 600;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-size: 1rem;
}

.submit-button:hover {
  background: var(--secondary-color);
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

/* Schedule Section */
.schedule {
  padding: 5rem 0;
  background: var(--bg-light);
}

.schedule h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--primary-color);
}

.schedule-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.schedule-card {
  background: var(--bg-light);
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: 2rem;
  text-align: center;
  text-decoration: none;
  color: var(--text-dark);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.schedule-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
}

.schedule-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-color);
}

.schedule-card h3 {
  font-size: 1.3rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.schedule-date {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-color);
}

/* About Section */
.about {
  background: var(--bg-gray);
  padding: 5rem 0;
}

.about h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--primary-color);
}

.about-content {
  max-width: 900px;
  margin: 0 auto;
  line-height: 1.8;
}

.about-content p {
  margin-bottom: 1.5rem;
  font-size: 1.1rem;
}

.invitation-highlight {
  background: var(--primary-color);
  color: var(--text-light);
  padding: 2rem;
  border-radius: var(--border-radius);
  margin: 2rem 0;
  position: relative;
}

.invitation-highlight::before {
  content: '"';
  position: absolute;
  top: -10px;
  left: 20px;
  font-size: 4rem;
  color: var(--accent-color);
  font-family: serif;
}

/* Organizing Section */
.organizing {
  padding: 5rem 0;
  background: var(--bg-light);
}

.organizing h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--primary-color);
}

.organizing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 4rem;
}

.org-card {
  background: var(--bg-light);
  padding: 2rem;
  border-radius: var(--border-radius);
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.org-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.org-logo {
  font-size: 3rem;
  color: var(--primary-color);
  margin-bottom: 1rem;
}

.org-card h3 {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
}

/* Committees */
.committees {
  margin-top: 4rem;
}

.committees h3 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 2rem;
  color: var(--primary-color);
}

.committees-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
}

.committee {
  background: var(--bg-gray);
  padding: 2rem;
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.committee h4 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.committee ul {
  list-style: none;
  margin-bottom: 1rem;
}

.committee li {
  padding: 0.3rem 0;
  border-bottom: 1px solid var(--border-color);
}

.committee li:last-child {
  border-bottom: none;
}

.committee span {
  color: var(--text-muted);
  font-style: italic;
}

/* Institutions Section */
.institutions {
  background: var(--bg-gray);
  padding: 5rem 0;
}

.institutions h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--primary-color);
}

.institutions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.institution-logo {
  background: var(--bg-light);
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  transition: var(--transition);
  font-size: 2rem;
  color: var(--primary-color);
}

.institution-logo:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-hover);
}

.institutions-note {
  text-align: center;
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto;
}

/* Location Section */
.location {
  padding: 5rem 0;
  background: var(--bg-light);
}

.location h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--primary-color);
}

.location-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

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

.hotel-logo-img {
  max-width: 200px;
  height: auto;
  margin-bottom: 2rem;
}

.location-info h3 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.address {
  font-size: 1.1rem;
  line-height: 1.6;
  margin-bottom: 2rem;
}

.hotel-rates {
  display: inline-block;
  background: var(--accent-color);
  color: var(--text-dark);
  padding: 1rem 2rem;
  text-decoration: none;
  border-radius: var(--border-radius);
  font-weight: 600;
  transition: var(--transition);
}

.hotel-rates:hover {
  background: #e67e22;
  transform: translateY(-2px);
}

.map-placeholder {
  background: var(--bg-gray);
  height: 300px;
  border-radius: var(--border-radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border: 2px dashed var(--border-color);
}

.map-placeholder i {
  font-size: 3rem;
  color: var(--primary-color);
  margin-bottom: 1rem;
}

/* Registration Section */
.registration {
  background: var(--bg-gray);
  padding: 5rem 0;
}

.registration h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.registration-subtitle {
  text-align: center;
  font-size: 1.2rem;
  margin-bottom: 3rem;
  color: var(--text-muted);
}

.registration-tabs {
  display: flex;
  justify-content: center;
  margin-bottom: 3rem;
  border-bottom: 2px solid var(--border-color);
}

.tab-button {
  background: none;
  border: none;
  padding: 1rem 2rem;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  transition: var(--transition);
  border-bottom: 3px solid transparent;
}

.tab-button.active {
  color: var(--primary-color);
  border-bottom-color: var(--primary-color);
}

.tab-button:hover {
  color: var(--primary-color);
}

.tab-content {
  display: none;
  max-width: 600px;
  margin: 0 auto;
}

.tab-content.active {
  display: block;
}

.registration-form {
  background: var(--bg-light);
  padding: 3rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

.form-group {
  margin-bottom: 2rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
  color: var(--text-dark);
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 1rem;
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  font-size: 1rem;
  transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(44, 90, 160, 0.1);
}

.checkbox-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.checkbox-group input {
  width: auto;
}

.payment-section {
  border-top: 2px solid var(--border-color);
  padding-top: 2rem;
  margin-top: 2rem;
}

.payment-section h4 {
  font-size: 1.3rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.payment-info {
  background: var(--bg-gray);
  padding: 2rem;
  border-radius: var(--border-radius);
  margin: 2rem 0;
}

.pdf-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 600;
  margin-top: 1rem;
}

.pdf-link:hover {
  color: var(--secondary-color);
}

.beca-info {
  background: #e8f4fd;
  padding: 2rem;
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
  margin: 2rem 0;
}

.registration-note {
  text-align: center;
  margin-top: 3rem;
  color: var(--text-muted);
}

/* Footer */
.footer {
  background: var(--bg-dark);
  color: var(--text-light);
  padding: 3rem 0 1rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 3rem;
  margin-bottom: 2rem;
}

.footer-logo-img {
  max-width: 150px;
  height: auto;
  filter: brightness(0) invert(1);
}

.footer-info p {
  margin-bottom: 1rem;
  opacity: 0.8;
}

.footer-links h4,
.footer-social h4 {
  margin-bottom: 1rem;
  color: var(--accent-color);
}

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

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

.footer-links a {
  color: var(--text-light);
  text-decoration: none;
  opacity: 0.8;
  transition: var(--transition);
}

.footer-links a:hover {
  opacity: 1;
  color: var(--accent-color);
}

.social-links {
  display: flex;
  gap: 1rem;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--primary-color);
  color: var(--text-light);
  border-radius: 50%;
  text-decoration: none;
  transition: var(--transition);
}

.social-links a:hover {
  background: var(--accent-color);
  transform: translateY(-2px);
}

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  opacity: 0.6;
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background-color: var(--bg-light);
    width: 100%;
    text-align: center;
    transition: 0.3s;
    box-shadow: var(--shadow);
    padding: 2rem 0;
  }

  .nav-menu.active {
    left: 0;
  }

  .nav-toggle {
    display: flex;
  }

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

  .hero-date {
    font-size: 1.2rem;
  }

  .countdown {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

  .countdown-item {
    padding: 1rem;
  }

  .countdown-number {
    font-size: 2rem;
  }

  .work-actions {
    flex-direction: column;
    gap: 1rem;
  }

  .location-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .registration-tabs {
    flex-wrap: wrap;
  }

  .tab-button {
    flex: 1;
    min-width: 120px;
  }

  .registration-form {
    padding: 2rem 1rem;
  }

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

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

  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 15px;
  }

  .hero {
    padding: 100px 0 60px;
  }

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

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

  .institutions-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

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

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.05);
  }
}

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

.pulse {
  animation: pulse 2s infinite;
}

/* PayPal Button Styling */
.paypal-button-container {
  margin-top: 1.5rem;
  padding: 1rem;
  background: #f8f9fa;
  border: 2px solid #e1e8ed;
  border-radius: var(--border-radius);
}

#paypal-button-argentinos,
#paypal-button-extranjeros,
#paypal-button-becas {
  min-height: 50px;
}

paypal-button {
  display: block;
  width: 100%;
  min-height: 50px;
  background: #0070ba;
  color: white;
  border: none;
  border-radius: var(--border-radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
  line-height: 50px;
  box-shadow: 0 2px 8px rgba(0, 112, 186, 0.2);
}

paypal-button:hover {
  background: #005ea6;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 112, 186, 0.3);
}

paypal-button:disabled {
  background: #cccccc;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* Payment Success/Error Messages */
.payment-message {
  margin: 15px 0;
  padding: 15px;
  border-radius: var(--border-radius);
  font-weight: 500;
}

.payment-success {
  background: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
}

.payment-error {
  background: #f8d7da;
  color: #721c24;
  border: 1px solid #f5c6cb;
}

.payment-cancelled {
  background: #fff3cd;
  color: #856404;
  border: 1px solid #ffeeba;
}