/* ==========================================================================
   HEADER / NAV
   ========================================================================== */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: var(--space-4) 0;
  transition: background var(--dur-base) var(--ease-out),
              border-color var(--dur-base) var(--ease-out),
              padding var(--dur-base) var(--ease-out);
  border-bottom: 1px solid transparent;
}

.site-header.is-scrolled {
  background: rgba(7, 13, 26, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom-color: var(--border-glass);
  padding: var(--space-3) 0;
}

.nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: var(--tracking-tight);
}

.brand-mark {
  width: 30px;
  height: 30px;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.nav-links a {
  font-size: var(--fs-body-sm);
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: var(--space-2) 0;
  transition: color var(--dur-fast) var(--ease-out);
}

.nav-links a:hover, .nav-links a[aria-current="page"] { color: var(--text-primary); }

.nav-links a::after {
  content: '';
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 2px;
  background: var(--grad-primary);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur-base) var(--ease-out);
}

.nav-links a:hover::after, .nav-links a[aria-current="page"]::after { transform: scaleX(1); }

.nav-actions { display: flex; align-items: center; gap: var(--space-3); }

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-glass-strong);
}

.nav-toggle svg { width: 18px; height: 18px; }

@media (max-width: 880px) {
  .nav-links {
    position: fixed;
    top: 64px;
    left: var(--space-4);
    right: var(--space-4);
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-1);
    background: var(--surface);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    box-shadow: var(--shadow-card);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--dur-base) var(--ease-out), opacity var(--dur-base) var(--ease-out);
  }
  .nav-links.is-open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-links a {
    padding: var(--space-3) var(--space-3);
    border-radius: var(--radius-sm);
  }
  .nav-links a:hover { background: rgba(255,255,255,0.04); }
  .nav-links a::after { display: none; }
  .nav-toggle { display: flex; }
  .nav-actions .btn-ghost { display: none; }
}