/* =============================================
   NAVIGATION
   ============================================= */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-height);
  background: oklch(from var(--color-bg) l c h / 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background 0.4s ease;
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-8);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: height 0.3s ease;
}

.nav.scrolled .nav-inner { height: 52px; }

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  list-style: none;
}
.nav-links a {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
  transition: color var(--transition-fast);
  position: relative;
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px; left: 0;
  width: 0; height: 1px;
  background: var(--color-primary);
  transition: width var(--transition-base);
}
.nav-links a:hover,
.nav-links a.active { color: var(--color-primary); }
.nav-links a:hover::after,
.nav-links a.active::after { width: 100%; }

.nav-right {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.theme-toggle {
  width: 36px; height: 36px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-interactive);
  cursor: none;
}
.theme-toggle:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  box-shadow: 0 0 12px oklch(0.7 0.2 195 / 0.2);
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 6px;
  cursor: none;
}
.hamburger span {
  display: block;
  width: 22px; height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all 0.3s ease;
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile nav drawer */
.mobile-nav {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--color-bg);
  z-index: 999;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
.mobile-nav.open {
  display: flex;
  opacity: 1;
  pointer-events: all;
}
.mobile-nav a {
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: 600;
  color: var(--color-text);
  transition: color var(--transition-fast);
}
.mobile-nav a:hover { color: var(--color-primary); }