#scroll-sentinel {
  position: absolute;
  top: 0; left: 0;
  width: 1px; height: 8px;
  pointer-events: none;
}

.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 50;
  background: transparent;
  transition: background-color var(--duration-hover) var(--ease-standard), box-shadow var(--duration-hover) var(--ease-standard);
}
.site-header.is-scrolled {
  background: var(--color-bg-dark);
  border-bottom: 1px solid var(--color-border-on-dark);
}
.site-header__topbar {
  margin: 0;
  padding-block: 10px;
  text-align: center;
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-fg-on-dark);
  opacity: 0.8;
  border-bottom: 1px solid var(--color-border-on-dark);
  overflow: hidden;
  max-height: 40px;
  transition: max-height var(--duration-reveal) var(--ease-standard), opacity var(--duration-hover) var(--ease-standard), padding-block var(--duration-reveal) var(--ease-standard), border-color var(--duration-reveal) var(--ease-standard);
}
.site-header.is-scrolled .site-header__topbar {
  max-height: 0;
  padding-block: 0;
  opacity: 0;
  border-bottom-color: transparent;
}
@media (prefers-reduced-motion: reduce) {
  .site-header__topbar { transition: none; }
}
.site-header__row {
  position: relative;
  z-index: 41;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding-block: var(--space-3);
}
.site-header__logo {
  grid-column: 2;
  justify-self: center;
  display: flex;
  align-items: center;
  transition: opacity var(--duration-hover) var(--ease-standard);
}
.site-header__logo:hover { opacity: 0.8; }
.site-header__logo-img--wordmark { display: none; }
.site-header.is-scrolled .site-header__logo-img--mark { display: none; }
.site-header.is-scrolled .site-header__logo-img--wordmark { display: block; }

.site-header__actions { grid-column: 3; justify-self: end; display: flex; align-items: center; gap: var(--space-2); }
.lang-switch {
  display: inline-flex; align-items: center; gap: 2px;
  background: none; border: 1px solid var(--color-border-on-dark);
  color: var(--color-fg-on-dark);
  padding: 4px 6px; border-radius: 999px;
}
.lang-switch__option {
  background: none; border: none;
  font-family: inherit;
  font-size: var(--text-xs); letter-spacing: 0.02em;
  color: var(--color-fg-secondary-on-dark);
  padding: 4px 9px; border-radius: 999px;
  cursor: pointer;
  transition: background-color var(--duration-hover) var(--ease-standard), color var(--duration-hover) var(--ease-standard), transform var(--duration-press) ease-out;
}
.lang-switch__option:hover { color: var(--color-fg-on-dark); }
.lang-switch__option:active { transform: scale(0.92); }
.lang-switch__option.is-active {
  background: var(--color-fg-on-dark);
  color: var(--color-bg-dark);
  font-weight: 600;
}
@media (prefers-reduced-motion: reduce) {
  .lang-switch__option:active { transform: none; }
}

.nav-toggle {
  grid-column: 1;
  justify-self: start;
  display: inline-flex; flex-direction: column; justify-content: center; gap: 5px;
  width: 32px; height: 32px; background: none; border: none; cursor: pointer;
  transition: transform var(--duration-press) ease-out;
}
.nav-toggle:active { transform: scale(0.9); }
.nav-toggle span { display: block; width: 100%; height: 2px; flex: 0 0 auto; background: var(--color-fg-on-dark); border-radius: 2px; }
@media (prefers-reduced-motion: reduce) {
  .nav-toggle:active { transform: none; }
}

.mobile-menu {
  position: fixed; inset: 0;
  background: rgba(0, 0, 0, 0.5);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--duration-reveal) var(--ease-standard), visibility 0s var(--duration-reveal);
  z-index: 40;
}
.mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
  transition: opacity var(--duration-reveal) var(--ease-standard), visibility 0s;
}
.mobile-menu__panel {
  position: absolute;
  top: 0; left: 0; bottom: 0;
  width: min(340px, 82vw);
  background: rgba(6, 10, 8, 0.88);
  display: flex; flex-direction: column;
  padding-block: var(--space-7) var(--space-5);
  padding-inline: var(--space-5);
  box-shadow: 0 0 48px rgba(0, 0, 0, 0.5);
  transform: translateX(-100%);
  transition: transform var(--duration-reveal) var(--ease-standard);
}
.mobile-menu.is-open .mobile-menu__panel {
  transform: translateX(0);
}
.mobile-menu__links {
  display: flex; flex-direction: column; gap: var(--space-4);
  margin-block: auto;
}
.mobile-menu__panel a { color: var(--color-fg-on-dark); }
.mobile-menu__links a {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: 300;
  display: inline-block;
  transition: transform var(--duration-press) ease-out, opacity var(--duration-hover) var(--ease-standard);
}
.mobile-menu__links a:active { transform: scale(0.96); opacity: 0.7; }
.mobile-menu__links a.is-active { color: var(--color-accent); }
.mobile-menu__footer {
  display: flex; flex-direction: column; gap: var(--space-2);
  border-top: 1px solid var(--color-border-on-dark);
  padding-top: var(--space-3);
}
.mobile-menu__tagline {
  margin: 0 0 var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  color: var(--color-fg-secondary-on-dark);
}
.mobile-menu__socials { display: flex; gap: var(--space-2); }
.mobile-menu__social {
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px;
  border: 1px solid var(--color-border-on-dark);
  border-radius: 50%;
  color: var(--color-fg-on-dark);
  transition: border-color var(--duration-hover) var(--ease-standard), opacity var(--duration-hover) var(--ease-standard), transform var(--duration-press) ease-out;
}
.mobile-menu__social:hover { opacity: 0.75; border-color: var(--color-fg-on-dark); }
.mobile-menu__social:active { transform: scale(0.88); }
body.menu-open { overflow: hidden; }
@media (prefers-reduced-motion: reduce) {
  .mobile-menu__panel { transition: none; }
  .mobile-menu__links a:active, .mobile-menu__social:active { transform: none; }
}

.site-footer {
  background: var(--color-bg-dark);
  color: var(--color-fg-on-dark);
  padding-block: var(--space-6) var(--space-4);
}
.site-footer a { opacity: 0.7; transition: opacity var(--duration-hover) var(--ease-standard); }
.site-footer a:hover { opacity: 1; }
.site-footer__grid {
  display: grid; gap: var(--space-4);
  grid-template-columns: 1fr;
}
.site-footer__credit {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-bottom: var(--space-4);
  margin-bottom: var(--space-4);
  border-bottom: 1px solid var(--color-border-on-dark);
}
.site-footer__credit-brand { display: flex; align-items: center; gap: var(--space-3); }
.site-footer__credit-brand img {
  display: block;
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 8px 14px;
}
.site-footer__credit-brand p { margin: 0; font-size: var(--text-sm); color: var(--color-fg-secondary-on-dark); }
.site-footer__credit .site-footer__credit-link {
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-accent);
  opacity: 1;
}
.site-footer__credit .site-footer__credit-link:hover { opacity: 0.8; }

.site-footer__bottom {
  border-top: 1px solid var(--color-border-on-dark);
  margin-top: var(--space-4);
  padding-top: var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-fg-secondary-on-dark);
  text-align: center;
}
@media (min-width: 768px) {
  .site-footer__grid { grid-template-columns: repeat(3, 1fr); }
}