/* ===========================
   🔹 HEADER (FANCY VERSION)
=========================== */
header {
  background: linear-gradient(120deg, var(--navy-1), var(--navy-2), var(--purple));
  background-size: 400% 400%;
  animation: gradientShift 20s ease infinite; /* same as body */
  backdrop-filter: blur(10px);
  text-align: center;
  padding: 15px 25px 10px;
  box-shadow: 0 0 25px rgba(0, 200, 255, 0.2), 0 0 40px rgba(255, 67, 197, 0.1);
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid rgba(0, 200, 255, 0.2);
}

header::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 90%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan), transparent);
  opacity: 0.6;
}

.logo {
  width: 80px;
  filter: drop-shadow(0 0 18px rgba(0, 200, 255, 0.9))
          drop-shadow(0 0 30px rgba(255, 67, 197, 0.6));
  transition: transform 0.4s ease, filter 0.4s ease;
}

.logo:hover {
  transform: scale(1.1);
  filter: drop-shadow(0 0 25px rgba(0, 200, 255, 1))
          drop-shadow(0 0 40px rgba(255, 67, 197, 0.9));
}

header h1 {
  color: var(--cyan);
  margin-top: 10px;
  font-size: 1.5rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  background: linear-gradient(90deg, var(--cyan), var(--magenta), var(--cyan));
  background-clip: text;
  -webkit-background-clip: text;
  color: transparent;
  animation: titleGlow 8s linear infinite;
  text-shadow: 0 0 20px rgba(0, 200, 255, 0.4);
}

nav {
  margin-top: 12px;
}

nav a {
  color: var(--text-light);
  margin: 0 18px;
  text-decoration: none;
  font-weight: 500;
  position: relative;
  transition: color 0.3s, text-shadow 0.3s;
}

nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -5px;
  width: 0%;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--magenta));
  transition: width 0.3s ease;
}

nav a:hover,nav a.active {
  color: var(--cyan);
  text-shadow: 0 0 8px var(--cyan);
}

nav a:hover::after {
  width: 100%;
}

@media (max-width: 768px) {
  header {
    padding: 12px 18px 8px;
  }

  .logo {
    width: 60px;
  }

  header h1 {
    font-size: 1.1rem;
    letter-spacing: 1px;
  }

  nav a {
    margin: 0 10px;
    font-size: 0.85rem;
  }
}