/* ============ NAV — site-header ============ */

/* ---- Shell ---- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-header);
  height: var(--header-h);
  /* transparent at top of page */
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur) var(--ease-out);
}

/* Frosted bar is painted on a pseudo-element — NOT on the header itself.
   Putting backdrop-filter on .site-header would make it the containing block
   for the position:fixed mobile menu it contains, collapsing the open menu to
   the 76px header box once .is-scrolled is applied (the "menu won't show after
   scrolling" bug). A pseudo-element keeps the frost without that side effect. */
.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(18px) saturate(160%);
  -webkit-backdrop-filter: blur(18px) saturate(160%);
  opacity: 0;
  transition: opacity var(--dur) var(--ease-out);
  pointer-events: none;
}

/* Scrolled state — JS adds .is-scrolled after 24px */
.site-header.is-scrolled::before { opacity: 1; }
.site-header.is-scrolled { border-bottom-color: var(--line); }

/* ---- Inner flex row ---- */
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  height: 100%;
  padding-inline: var(--gutter);
  max-width: var(--container-wide);
  margin-inline: auto;
}

/* ---- Brand ---- */
.site-header__brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
  text-decoration: none;
  color: var(--text);
  outline-offset: 6px;
}

.site-header__mark {
  width: 32px;
  height: 32px;
  flex-shrink: 0;
  transition: transform var(--dur-fast) var(--ease-out);
}
.site-header__brand:hover .site-header__mark {
  transform: rotate(-6deg) scale(1.08);
}

.site-header__wordmark {
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
  color: var(--text);
  line-height: 1;
  white-space: nowrap;
}

.site-header__sub {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-faint);
  padding: 0.25em 0.55em;
  border: 1px solid var(--line);
  border-radius: var(--r-pill);
  line-height: 1.4;
  margin-left: var(--space-1);
  transition: border-color var(--dur-fast) var(--ease-out), color var(--dur-fast) var(--ease-out);
}
.site-header__brand:hover .site-header__sub {
  border-color: var(--accent-line);
  color: var(--accent-bright);
}

/* ---- Desktop nav ---- */
.site-header__nav {
  flex: 1;
  display: flex;
  justify-content: center;
}

.site-header__links {
  display: flex;
  align-items: center;
  gap: clamp(0.25rem, 2.4vw, 2rem);
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-header__link {
  position: relative;
  font-family: var(--font-sans);
  font-size: var(--fs-small);
  font-weight: 500;
  letter-spacing: 0.01em;
  color: var(--text-dim);
  padding: 0.35em 0.5em;
  border-radius: var(--r-sm);
  white-space: nowrap;
  transition: color var(--dur-fast) var(--ease-out);
  outline-offset: 4px;
}
.site-header__link::after {
  content: "";
  position: absolute;
  left: 0.5em;
  right: 0.5em;
  bottom: -2px;
  height: 1.5px;
  background: var(--accent-bright);
  border-radius: var(--r-pill);
  transform: scaleX(0);
  transform-origin: right center;
  transition: transform var(--dur) var(--ease-out);
}
.site-header__link:hover {
  color: var(--text);
}
.site-header__link:hover::after {
  transform: scaleX(1);
  transform-origin: left center;
}
.site-header__link.is-active {
  color: var(--text);
}
.site-header__link.is-active::after {
  transform: scaleX(1);
  background: var(--accent);
}

/* ---- Desktop CTA ---- */
.site-header__cta {
  flex-shrink: 0;
  /* small size override */
  font-size: 0.85rem;
  padding: 0.65em 1.2em;
}

/* ---- Hamburger button ---- */
.site-header__toggle {
  display: none; /* shown on mobile only */
  position: relative;
  z-index: calc(var(--z-overlay) + 1);
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  border-radius: var(--r-sm);
  flex-shrink: 0;
  transition: background var(--dur-fast) var(--ease-out);
  outline-offset: 4px;
}
.site-header__toggle:hover {
  background: var(--surface-2);
}

/* Three-bar burger icon */
.site-header__burger {
  display: flex;
  flex-direction: column;
  gap: 5px;
  width: 22px;
}
.site-header__burger span {
  display: block;
  height: 2px;
  background: var(--text);
  border-radius: var(--r-pill);
  transform-origin: center;
  transition:
    transform var(--dur) var(--ease-spring),
    opacity var(--dur-fast) var(--ease-out),
    width var(--dur) var(--ease-out);
}
.site-header__burger span:nth-child(1) { width: 22px; }
.site-header__burger span:nth-child(2) { width: 16px; }
.site-header__burger span:nth-child(3) { width: 22px; }

/* Animate to X when menu open */
.site-header__toggle[aria-expanded="true"] .site-header__burger span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
  width: 22px;
}
.site-header__toggle[aria-expanded="true"] .site-header__burger span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
.site-header__toggle[aria-expanded="true"] .site-header__burger span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
  width: 22px;
}

/* ---- Mobile fullscreen menu ---- */
.site-header__menu {
  position: fixed;
  inset: 0;
  z-index: var(--z-overlay);
  background: var(--bg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-inline: var(--gutter);
  padding-block: var(--space-8);
  /* hidden state */
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition:
    opacity var(--dur) var(--ease-out),
    transform var(--dur) var(--ease-out),
    visibility 0s linear var(--dur);
  overflow: auto;
  isolation: isolate;
}
.site-header__menu.is-open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  transition:
    opacity var(--dur) var(--ease-out),
    transform var(--dur) var(--ease-out),
    visibility 0s linear 0s;
}

/* ambient glow inside menu */
.site-header__menu-glow {
  position: absolute;
  width: 480px;
  height: 480px;
  top: -120px;
  right: -80px;
  border-radius: 50%;
  filter: blur(90px);
  opacity: 0.35;
  pointer-events: none;
  z-index: 0;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
}

.site-header__menu-nav {
  position: relative;
  z-index: 1;
  max-width: 560px;
  margin: 0 auto;
  width: 100%;
}

.site-header__menu-links {
  list-style: none;
  margin: 0 0 var(--space-7) 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.site-header__menu-link {
  display: block;
  font-family: var(--font-sans);
  font-size: clamp(2rem, 7vw, 3.2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-dim);
  padding: 0.3em 0;
  border-bottom: 1px solid var(--line-faint);
  line-height: 1.1;
  transition:
    color var(--dur-fast) var(--ease-out),
    padding-left var(--dur-fast) var(--ease-out);
  outline-offset: 6px;
  /* min tap target guaranteed by line-height + padding */
  min-height: 44px;
}
.site-header__menu-link:hover,
.site-header__menu-link:focus-visible {
  color: var(--text);
  padding-left: 0.4em;
}
.site-header__menu-link.is-active {
  color: var(--accent-bright);
}

.site-header__menu-cta {
  margin-bottom: var(--space-7);
  align-self: flex-start;
}

.site-header__menu-tag {
  color: var(--text-faint);
  font-size: var(--fs-label);
}
/* .eyebrow is already applied — override color only */
.site-header__menu-tag.eyebrow {
  color: var(--text-faint);
}

/* ---- Responsive: hide / show elements ---- */
@media (max-width: 900px) {
  /* Hide desktop nav and CTA */
  .site-header__nav {
    display: none;
  }
  /* Show hamburger */
  .site-header__toggle {
    display: flex;
  }
}

@media (min-width: 901px) {
  /* Menu is never needed on desktop — keep it from interfering */
  .site-header__menu {
    display: none;
  }
}

/* Fine-tune desktop nav gaps for mid-range viewport */
@media (max-width: 1200px) and (min-width: 901px) {
  .site-header__links {
    gap: clamp(0.25rem, 1.6vw, 1.5rem);
  }
  .site-header__link {
    font-size: 0.8rem;
  }
}

/* ---- Reduced motion ---- */
@media (prefers-reduced-motion: reduce) {
  .site-header,
  .site-header__menu,
  .site-header__link::after,
  .site-header__burger span,
  .site-header__mark {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
  }
}