body {
  font-family: 'Segoe UI', sans-serif;
  background: #f4f4f9;
  color: #333;
  margin: 0;
  padding: 0;
}

header {
  background: linear-gradient(to right, #4e54c8, #8f94fb);
  color: white;
  padding: 2rem;
  text-align: center;
}

.tagline {
  font-style: italic;
  opacity: 0.9;
}

.nav-tabs {
  display: flex;
  justify-content: center;
  background: #fff;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  padding: 1rem;
}

.nav-tabs button {
  background: none;
  border: none;
  font-size: 1rem;
  margin: 0 1rem;
  cursor: pointer;
  color: #555;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid transparent;
  transition: all 0.3s ease;
}

.nav-tabs button:hover {
  color: #4e54c8;
  border-bottom: 2px solid #4e54c8;
}

main {
  max-width: 800px;
  margin: auto;
  padding: 2rem;
  background: white;
  margin-top: 1rem;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.section {
  display: none;
}

.section.active {
  display: block;
}

.section h2 {
  color: #4e54c8;
  margin-bottom: 1rem;
}

ul {
  padding-left: 20px;
}

.warning {
  background: #fff3cd;
  padding: 1rem;
  border: 1px solid #ffeeba;
  border-radius: 5px;
  margin-top: 1rem;
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
  background: #f0f0f0;
  margin-top: 2rem;
  color: #777;
}