/* ==========================================================
   NAVBAR.CSS — Fixed Navigation + Theme Toggle Button
   ========================================================== */
#navbar {
  position: fixed;
  top: 0; left: 0;
  width: 100%;
  z-index: 1000;
  padding: 1.25rem 0;
  transition: background var(--transition-theme),
              padding    var(--transition-smooth),
              box-shadow var(--transition-smooth);
}
#navbar.scrolled {
  background: var(--nav-scrolled-bg);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  padding: 0.75rem 0;
  box-shadow: 0 1px 0 var(--border);
}

.nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* ── Logo ── */
.nav-logo { display: flex; flex-direction: column; line-height: 1; }
.nav-logo-main {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: 1.8rem;
  letter-spacing: 0.05em;
  color: var(--text-primary);
  transition: color var(--transition-theme);
}
.nav-logo-main span { color: var(--color-cyan); }
.nav-logo-sub {
  font-size: 0.55rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-top: 2px;
}

/* ── Desktop Links ── */
.nav-links {
  display: flex;
  align-items: center;
  gap: 2.5rem;
}
.nav-links a {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  transition: color var(--transition-fast);
  position: relative;
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px; left: 0;
  width: 0; height: 2px;
  background: var(--color-cyan);
  transition: width var(--transition-smooth);
}
.nav-links a:hover,
.nav-links a.active { color: var(--text-primary); }
.nav-links a:hover::after,
.nav-links a.active::after { width: 100%; }

/* ── Right controls cluster (theme toggle + CTA) ── */
.nav-controls {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

/* ─────────────────────────────────────────────
   THEME TOGGLE BUTTON
───────────────────────────────────────────── */
.theme-toggle {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--bg-glass);
  color: var(--text-muted);
  transition: border-color var(--transition-fast),
              background   var(--transition-fast),
              color        var(--transition-fast),
              transform    var(--transition-smooth);
  flex-shrink: 0;
}
.theme-toggle:hover {
  border-color: var(--color-cyan);
  color: var(--color-cyan);
  background: var(--bg-glass-hv);
  transform: rotate(20deg) scale(1.08);
}
.theme-toggle svg { width: 18px; height: 18px; }

/* Sun icon — shown in dark mode */
.icon-sun  { display: block; }
.icon-moon { display: none; }

[data-theme="light"] .icon-sun  { display: none; }
[data-theme="light"] .icon-moon { display: block; }

/* ── Hamburger ── */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
  background: none;
  border: none;
}
.nav-hamburger span {
  display: block;
  width: 24px; height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--transition-smooth),
              opacity   var(--transition-smooth);
}
.nav-hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; }
.nav-hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ── Mobile Menu ── */
.nav-mobile {
  display: none;
  flex-direction: column;
  background: var(--nav-scrolled-bg);
  backdrop-filter: blur(18px);
  border-top: 1px solid var(--border);
  padding: var(--space-md) 0;
  position: absolute;
  top: 100%; left: 0;
  width: 100%;
}
.nav-mobile.open { display: flex; }
.nav-mobile a {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.9rem var(--space-lg);
  color: var(--text-muted);
  border-bottom: 1px solid var(--border);
  transition: color var(--transition-fast), background var(--transition-fast);
}
.nav-mobile a:hover,
.nav-mobile a.active { color: var(--text-primary); background: var(--bg-glass); }
.nav-mobile .mobile-controls {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
}
.nav-mobile .btn {
  flex: 1;
}

/* ── Responsive ── */
@media (max-width: 900px) {
  .nav-links           { display: none; }
  .nav-controls .btn   { display: inline-flex !important; padding: 0.6rem 1rem !important; font-size: 0.7rem !important; }
  .nav-hamburger       { display: flex; }
}