/* ============================================================
   Navigation — Fixed header + Fullscreen overlay menu
   ============================================================ */

/* --- Header --- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-lg) var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background var(--duration-med) var(--ease-out),
              padding var(--duration-med) var(--ease-out);
}

.site-header.scrolled {
  background: rgba(10, 10, 10, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding-top: var(--space-md);
  padding-bottom: var(--space-md);
}

/* --- Logo --- */
.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  z-index: 110;
}

.logo svg {
  width: 44px;
  height: auto;
}

.logo img {
  height: 36px;
  width: auto;
  display: block;
}

.logo-text {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-primary);
  opacity: 0;
  transform: translateX(-8px);
  transition: opacity var(--duration-med) var(--ease-out),
              transform var(--duration-med) var(--ease-out);
}

.logo:hover .logo-text {
  opacity: 1;
  transform: translateX(0);
}

/* --- Desktop nav links --- */
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
  list-style: none;
}

.nav-links a {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 400;
  letter-spacing: 0.04em;
  color: var(--text-secondary);
  position: relative;
  transition: color var(--duration-fast) var(--ease-out);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--accent);
  transition: width var(--duration-med) var(--ease-out);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

/* --- Hamburger --- */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  width: 28px;
  z-index: 110;
  padding: 4px 0;
}

.menu-toggle span {
  display: block;
  width: 100%;
  height: 1.5px;
  background: var(--text-primary);
  transition: transform var(--duration-med) var(--ease-out),
              opacity var(--duration-fast);
  transform-origin: center;
}

.menu-toggle.open span:nth-child(1) {
  transform: translateY(7.5px) rotate(45deg);
}
.menu-toggle.open span:nth-child(2) {
  opacity: 0;
}
.menu-toggle.open span:nth-child(3) {
  transform: translateY(-7.5px) rotate(-45deg);
}

/* --- Fullscreen overlay --- */
.nav-overlay {
  position: fixed;
  inset: 0;
  z-index: 105;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: var(--space-3xl) var(--gutter);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--duration-slow) var(--ease-out),
              visibility 0s var(--duration-slow);
}

.nav-overlay.open {
  opacity: 1;
  visibility: visible;
  transition: opacity var(--duration-slow) var(--ease-out),
              visibility 0s 0s;
}

.nav-overlay__inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  max-width: var(--container-max);
  margin: 0 auto;
  width: 100%;
  gap: var(--space-3xl);
}

.nav-overlay__links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.nav-overlay__links a {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 600;
  color: var(--text-muted);
  transition: color var(--duration-med) var(--ease-out),
              transform var(--duration-med) var(--ease-out);
  display: inline-block;
}

.nav-overlay__links a:hover {
  color: var(--text-primary);
  transform: translateX(12px);
}

.nav-overlay__links a.active {
  color: var(--accent);
}

/* Stagger-in for overlay links */
.nav-overlay.open .nav-overlay__links li {
  animation: overlayLinkIn 0.5s var(--ease-out) both;
}
.nav-overlay.open .nav-overlay__links li:nth-child(1) { animation-delay: 100ms; }
.nav-overlay.open .nav-overlay__links li:nth-child(2) { animation-delay: 160ms; }
.nav-overlay.open .nav-overlay__links li:nth-child(3) { animation-delay: 220ms; }
.nav-overlay.open .nav-overlay__links li:nth-child(4) { animation-delay: 280ms; }
.nav-overlay.open .nav-overlay__links li:nth-child(5) { animation-delay: 340ms; }
.nav-overlay.open .nav-overlay__links li:nth-child(6) { animation-delay: 400ms; }

@keyframes overlayLinkIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Overlay info column */
.nav-overlay__info {
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
  padding-top: var(--space-md);
}

.nav-overlay__info-group h4 {
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: var(--space-sm);
}

.nav-overlay__info-group p,
.nav-overlay__info-group a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.nav-overlay__info-group a:hover {
  color: var(--accent);
}

.nav-overlay__socials {
  display: flex;
  gap: var(--space-lg);
  list-style: none;
}

.nav-overlay__socials a {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  transition: color var(--duration-fast);
}

.nav-overlay__socials a:hover {
  color: var(--accent);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .menu-toggle {
    display: flex;
  }
  .nav-overlay__inner {
    flex-direction: column;
    gap: var(--space-2xl);
  }
  .nav-overlay__info {
    border-top: 1px solid var(--border);
    padding-top: var(--space-xl);
  }
}