/* ==========================================================================
   OrchardTech Greenova — layout.css
   Header / nav / language toggle / mobile menu / footer / back-to-top
   ========================================================================== */

/* ---------- Header (§7.4) ---------- */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 200;
  height: 72px;
  background: rgba(246, 249, 247, .82);
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
  transition: background var(--dur-micro) ease-out,
              box-shadow var(--dur-micro) ease-out,
              border-color var(--dur-micro) ease-out;
  border-bottom: 1px solid var(--line);
}
.site-header__inner {
  height: 72px;
  display: flex;
  align-items: center;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
}
.brand img { width: 38px; height: 38px; }
.brand__name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.06rem;
  letter-spacing: -0.02em;
  color: var(--ink-900);
  line-height: 1.1;
}
.brand__name small {
  display: block;
  font-family: var(--font-body);
  font-weight: 500;
  font-size: .66rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-400);
}
/* Primary nav */
.site-nav { margin-inline: auto; }
.site-nav ul { display: flex; align-items: center; gap: clamp(14px, 1.6vw, 28px); }
.site-nav a {
  position: relative;
  display: inline-block;
  padding: 6px 2px;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--ink-500);
  transition: color var(--dur-micro) ease-out;
  white-space: nowrap;
}
.site-nav a:hover { color: var(--green-700); }
.site-nav a::after {
  content: "";
  position: absolute;
  left: 0; right: 100%; bottom: -2px;
  height: 2px;
  background: var(--grad-accent);
  transition: right var(--dur-micro) var(--ease-out);
}
.site-nav a:hover::after { right: 0; }
.site-nav a[aria-current="page"] { color: var(--green-700); font-weight: 600; }
.site-nav a[aria-current="page"]::after { right: 0; height: 3px; }

/* Header right cluster */
.header-actions { display: flex; align-items: center; gap: 14px; flex: none; margin-left: auto; }
.site-nav + .header-actions { margin-left: 0; }

/* Language toggle — segmented control */
.lang-toggle {
  display: inline-flex;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  padding: 3px;
  gap: 2px;
}
.lang-toggle button {
  padding: 4px 12px;
  border-radius: 999px;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--ink-500);
  transition: all var(--dur-micro) ease-out;
}
.lang-toggle button[aria-pressed="true"] {
  background: var(--accent-500);
  color: var(--green-950);
}

/* Hamburger */
.nav-toggle {
  display: none;
  width: 44px; height: 44px;
  position: relative;
  z-index: 260;
  border-radius: 10px;
  margin-right: 12px;
  flex: none;
}
.nav-toggle span {
  position: absolute; left: 11px; right: 11px;
  height: 2px; border-radius: 2px;
  background: var(--ink-900);
  transition: transform var(--dur-micro) var(--ease-out),
              opacity var(--dur-micro) ease-out, background var(--dur-micro) ease-out;
}
.nav-toggle span:nth-child(1) { top: 16px; }
.nav-toggle span:nth-child(2) { top: 22px; }
.nav-toggle span:nth-child(3) { top: 28px; }
body.menu-open .nav-toggle span { background: #F6F9F7; }
body.menu-open .nav-toggle span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
body.menu-open .nav-toggle span:nth-child(2) { opacity: 0; }
body.menu-open .nav-toggle span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* Mobile menu close button */
.mobile-menu__close {
  position: absolute;
  top: 18px; right: 12px;
  width: 44px; height: 44px;
  z-index: 270;
  border-radius: 10px;
}
.mobile-menu__close span {
  position: absolute; left: 11px; right: 11px;
  height: 2px; border-radius: 2px;
  background: #F6F9F7;
  top: 21px;
}
.mobile-menu__close span:nth-child(1) { transform: rotate(45deg); }
.mobile-menu__close span:nth-child(2) { transform: rotate(-45deg); }

/* Mobile menu (§7.4) */
.mobile-menu {
  position: fixed; inset: 0;
  z-index: 250;
  background: var(--green-950);
  display: flex;
  flex-direction: column;
  padding: 110px var(--gutter) 40px;
  transform: translateX(100%);
  visibility: hidden;
  transition: transform 320ms var(--ease-out), visibility 0s 320ms;
}
body.menu-open .mobile-menu { transform: none; visibility: visible; transition-delay: 0s; }
.mobile-menu ul { display: flex; flex-direction: column; gap: 4px; }
.mobile-menu a {
  display: flex; align-items: baseline; gap: 14px;
  padding: 13px 0;
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 5.4vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: #F6F9F7;
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}
html[lang^="zh"] .mobile-menu a { font-family: var(--font-zh); }
.mobile-menu a .idx {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--accent-500);
  letter-spacing: .1em;
}
.mobile-menu a[aria-current="page"] { color: var(--accent-300); }
.mobile-menu__foot {
  margin-top: auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  padding-top: 28px;
}
.mobile-menu .lang-toggle { border-color: rgba(255, 255, 255, .3); }
.mobile-menu .lang-toggle button { color: rgba(246, 249, 247, .8); }
.mobile-menu .lang-toggle button[aria-pressed="true"] { background: var(--accent-500); color: var(--green-950); }

/* ---------- Footer (§7.7) ---------- */
.site-footer {
  background: var(--green-950);
  color: #B9CCC4;
  padding: clamp(56px, 7vw, 88px) 0 32px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255, 255, 255, .12);
}
.footer-brand .brand__name { color: #F6F9F7; }
.footer-brand .brand__name small { color: rgba(246, 249, 247, .55); }
.footer-brand p { font-size: var(--text-sm); color: #8FA79E; margin: 18px 0 20px; max-width: 34ch; }
.site-footer h2 {
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: #7FA195;
  margin-bottom: 20px;
}
html[lang^="zh"] .site-footer h2 { letter-spacing: .06em; }
.site-footer ul { display: flex; flex-direction: column; gap: 12px; }
.site-footer ul a, .site-footer li {
  font-size: var(--text-sm);
  color: #B9CCC4;
}
.site-footer ul a { transition: color var(--dur-micro) ease-out; display: inline-flex; align-items: center; gap: 6px; }
.site-footer ul a:hover { color: var(--accent-300); }
.footer-contact li { display: flex; gap: 10px; align-items: flex-start; font-size: var(--text-sm); }
.footer-contact svg { flex: none; width: 16px; height: 16px; margin-top: 5px; color: var(--accent-500); }
.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding-top: 28px;
  font-size: var(--text-xs);
  color: #6E857C;
}
.footer-legal nav { display: flex; gap: 18px; }
.footer-legal a { color: #8FA79E; }
.footer-legal a:hover { color: var(--accent-300); }

/* ---------- Back to top (§6.10) ---------- */
.back-to-top {
  position: fixed;
  right: 24px; bottom: 24px;
  z-index: 150;
  width: 48px; height: 48px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: rgba(255, 255, 255, .72);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  border: 1px solid var(--line);
  color: var(--green-800);
  box-shadow: 0 8px 24px rgba(6, 42, 34, .12);
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity var(--dur-micro) ease-out, transform var(--dur-micro) ease-out;
}
.back-to-top.is-visible { opacity: 1; transform: none; pointer-events: auto; }
.back-to-top:hover { background: var(--green-800); color: #fff; border-color: var(--green-800); }

/* ---------- Responsive ---------- */
@media (max-width: 1120px) {
  .site-nav { display: none; }
  .site-nav + .header-actions { margin-left: auto; }
  .nav-toggle { display: block; }
}
@media (max-width: 860px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
}
@media (max-width: 520px) {
  .header-actions .lang-toggle { display: none; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-legal { flex-direction: column; align-items: flex-start; }
}