:root {
  color-scheme: dark;
  color: #111;
  background: #f7f8fb;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  line-height: 1.6;
  min-height: 100vh;
}

.hidden {
  display: none;
}

.hero.start-view {
  min-height: 12rem;
  overflow: hidden;
}

.hero.start-view .hero-content h1,
.hero.start-view .hero-content p {
  display: none;
}

.hero.start-view .hero-actions {
  padding: 2rem 0 1rem;
}

.back-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

img {
  max-width: 100%;
}

.container {
  width: min(1100px, calc(100% - 2rem));
  margin: 0 auto;
}

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

.logo {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.hero {
  background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
  color: white;
  padding: 5rem 0 4rem;
}

.hero-content {
  max-width: 680px;
}

.hero h1 {
  margin: 0 0 1rem;
  font-size: clamp(2.5rem, 4vw, 4rem);
  line-height: 1.05;
}

.hero p {
  margin: 0 0 1.75rem;
  font-size: 1.1rem;
  opacity: 0.95;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.95rem 1.5rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: #111827;
  color: #ffffff;
}

.btn-secondary {
  background: rgba(255,255,255,0.18);
  color: white;
  border: 1px solid rgba(255,255,255,0.28);
}

.section-light {
  padding: 5rem 0;
  background: white;
}

.section-dark {
  padding: 5rem 0;
  background: #111827;
  color: white;
}

.section-light h2,
.section-dark h2 {
  margin-top: 0;
  font-size: clamp(2rem, 2.5vw, 2.75rem);
}

.grid {
  display: grid;
  gap: 1.5rem;
  margin-top: 2rem;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.event-grid {
  display: grid;
  gap: 1.5rem;
  margin-top: 2rem;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.event-card {
  padding: 1.75rem;
  border-radius: 24px;
  background: #ffffff;
  border: 1px solid #e5e7eb;
  box-shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
}

.section-dark .event-card {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.16);
}

.event-card h3 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: 1.3rem;
}

.event-meta {
  margin: 0;
  color: #6b7280;
  font-size: 0.95rem;
}

.event-card p:last-child {
  margin-top: 1rem;
}

.feature-card {
  padding: 1.75rem;
  border-radius: 24px;
  background: #f3f4f6;
  box-shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

.section-dark .feature-card {
  background: rgba(255, 255, 255, 0.08);
}

.feature-card h3 {
  margin-top: 0;
}

.split {
  display: grid;
  gap: 2rem;
  align-items: center;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.split ul {
  padding-left: 1.2rem;
  margin: 1.5rem 0 0;
}

.split li {
  margin-bottom: 0.75rem;
}

.feature-image {
  display: grid;
  place-items: center;
}

.feature-image .card {
  width: 100%;
  max-width: 340px;
  min-height: 260px;
  border-radius: 32px;
  background: linear-gradient(180deg, rgba(255,255,255,0.16), rgba(255,255,255,0.04));
  display: grid;
  place-items: center;
  color: white;
  font-weight: 700;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  box-shadow: 0 24px 80px rgba(15, 23, 42, 0.35);
}

.contact-card {
  padding: 3rem;
  border-radius: 28px;
  background: #eef2ff;
}

.contact-grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 420px);
  align-items: start;
}

.contact-card h2 {
  margin-bottom: 0.75rem;
}

.registration-form {
  display: grid;
  gap: 1rem;
}

.registration-form label {
  display: grid;
  gap: 0.5rem;
  font-weight: 600;
}

.registration-form input,
.registration-form select {
  width: 100%;
  padding: 0.95rem 1rem;
  border-radius: 16px;
  border: 1px solid #d1d5db;
  font: inherit;
}

.registration-form input:focus,
.registration-form select:focus {
  outline: none;
  border-color: #4f46e5;
  box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.12);
}

.payment-options {
  border: 1px solid #d1d5db;
  border-radius: 20px;
  padding: 1rem 1.25rem;
}

.payment-options legend {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.payment-options label {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
}

@media (max-width: 860px) {
  .contact-grid {
    grid-template-columns: 1fr;
  }
}

.footer {
  padding: 2rem 0 2.5rem;
  background: #0f172a;
  color: #cbd5e1;
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  align-items: center;
}

@media (max-width: 740px) {
  .hero {
    padding-top: 4rem;
  }
  .split {
    grid-template-columns: 1fr;
  }
  .nav-bar {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
}