/* Reset and base */
*, *::before, *::after {
  box-sizing: border-box;
}
body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: #f5f7fa;
  color: #222;
  overflow-x: hidden;
}
a {
  text-decoration: none;
  color: inherit;
}

/* Navbar */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  background: #fff;
  border-bottom: 1px solid #ddd;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 1.5rem;
  height: 60px;
  z-index: 1000;
  perspective: 1000px;
}
.logo {
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: 1px;
  color: #333;
}
.nav-links {
  display: flex;
  gap: 1.5rem;
}
.nav-links a {
  font-weight: 600;
  transition: color 0.3s ease;
  position: relative;
}
.nav-links a:hover {
  color: #007bff;
}
/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 5px;
}
.hamburger div {
  width: 25px;
  height: 3px;
  background: #333;
  border-radius: 3px;
  transition: all 0.3s ease;
}

/* Mobile nav */
@media (max-width: 768px) {
  .nav-links {
    position: fixed;
    top: 60px; right: 0;
    background: #fff;
    height: calc(100vh - 60px);
    width: 200px;
    flex-direction: column;
    padding: 1rem;
    transform: translateX(100%);
    transition: transform 0.3s ease;
    box-shadow: -3px 0 10px rgba(0,0,0,0.1);
  }
  .nav-links.active {
    transform: translateX(0);
  }
  .hamburger {
    display: flex;
  }
}

/* Hero section */
header.hero {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  perspective: 1200px;
  padding: 0 1rem;
  text-align: center;
}
.card-3d {
  width: 320px;
  height: 420px;
  background: linear-gradient(145deg, #007bff, #00c6ff);
  border-radius: 20px;
  box-shadow: 0 15px 30px rgba(0,123,255,0.4);
  color: white;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-weight: 700;
  font-size: 2rem;
  cursor: grab;
  user-select: none;
  transform-style: preserve-3d;
  transition: box-shadow 0.3s ease;
}
.card-3d:hover {
  box-shadow: 0 25px 50px rgba(0,123,255,0.6);
}

/* Call to action button */
.btn-cta {
  margin-top: 2rem;
  padding: 0.85rem 2.2rem;
  font-size: 1.2rem;
  background: #fff;
  color: #007bff;
  font-weight: 700;
  border-radius: 40px;
  border: none;
  box-shadow: 0 5px 15px rgba(0,123,255,0.3);
  cursor: pointer;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  transform-style: preserve-3d;
}
.btn-cta:hover {
  transform: translateZ(20px) scale(1.05);
  box-shadow: 0 8px 25px rgba(0,123,255,0.6);
}

/* Section centering */
.section-center {
  padding: 4rem 1rem;
  max-width: 720px;
  margin: auto;
  text-align: center;
}

/* Footer */
footer {
  padding: 1.5rem;
  background: #e1e7f0;
  text-align: center;
  font-size: 0.9rem;
  color: #555;
  margin-top: 2rem;
}
footer a {
  margin: 0 0.75rem;
  color: #007bff;
}