/* ===== BASE ===== */
body {
  font-family: system-ui, sans-serif;
  background: #f6f7fb;
  color: #111;
  padding: 40px;
  transition: background .3s, color .3s;
}

main {
  margin-top: 120px;
}

/* ===== GLASS MENU ===== */
.glass-header {
  position: fixed;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1000;

  background: rgba(255,255,255,.7);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);

  padding: 8px;
  border-radius: 999px;
  box-shadow: 0 10px 30px rgba(0,0,0,.12);
}

.glass-header nav {
  display: flex;
  gap: 8px;
}

.nav {
  border: none;
  background: transparent;
  padding: 10px 18px;
  border-radius: 999px;
  cursor: pointer;
  transition: .3s;
}

.nav.active {
  background: #111;
  color: #fff;
}

/* ===== PAGE TRANSITION ===== */
.page {
  animation: fade .3s ease;
}

@keyframes fade {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== DARK MODE ===== */
body.dark {
  background: #0b0f19;
  color: #fff;
}

body.dark .glass-header {
  background: rgba(20,20,30,.7);
}

body.dark .nav.active {
  background: #2563eb;
}