/* ==========================================================================
   HEADER & NAVIGATION
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  height: var(--header-height);
  display: flex;
  align-items: center;
  background: var(--color-obsidian);
  border-bottom: 1px solid var(--color-graphite-border-dark);
}

.site-header.is-scrolled {
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

/* ---- Zone A: Logo ---- */

.site-header__logo {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 20px;
  letter-spacing: 0.01em;
  color: var(--color-white);
  padding: var(--space-2);
  margin: calc(var(--space-2) * -1);
}

/* ---- Zone B: Primary nav ---- */

.primary-nav {
  display: none;
}

@media (min-width: 1024px) {
  .primary-nav {
    display: flex;
    align-items: center;
    gap: 40px;
  }
}

.primary-nav__item {
  position: relative;
}

.primary-nav__trigger {
  display: flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: none;
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 14px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--color-white);
  padding: var(--space-2) 0;
  position: relative;
}

.primary-nav__trigger::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 100%;
  height: 1px;
  background: var(--color-royal-violet);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--dur-fast) var(--ease-out);
}

.primary-nav__item:not(.has-megamenu) .primary-nav__trigger:hover::after,
.primary-nav__item:not(.has-megamenu) .primary-nav__trigger:focus-visible::after {
  transform: scaleX(1);
}

/* ---- Mega-menu ---- */

.mega-menu {
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  z-index: var(--z-megamenu);
  background: var(--color-obsidian);
  border-top: 1px solid var(--color-graphite-border-dark);
  opacity: 0;
  transform: translateY(-8px);
  pointer-events: none;
  transition: opacity 220ms var(--ease-out-expo), transform 220ms var(--ease-out-expo);
}

.mega-menu.is-open {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.mega-menu__inner {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: var(--space-6);
  padding-block: var(--space-10);
}

.mega-menu__links {
  grid-column: span 8;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

.mega-menu__col-heading {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-graphite-300);
  margin-bottom: var(--space-4);
}

.mega-menu__link {
  display: block;
  font-family: var(--font-body);
  font-size: 15px;
  color: var(--color-white);
  padding-block: var(--space-2);
  transition: color var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out);
}

.mega-menu__link:hover,
.mega-menu__link:focus-visible {
  color: var(--color-royal-violet);
  transform: translateX(4px);
}

.mega-menu__feature {
  grid-column: span 4;
  border-left: 1px solid var(--color-graphite-border-dark);
  padding-left: var(--space-6);
}

.mega-menu__feature-graphic {
  width: 120px;
  height: 120px;
  margin-bottom: var(--space-4);
}

.mega-menu__feature-text {
  font-family: var(--font-body);
  font-size: 13px;
  line-height: 20px;
  color: var(--color-graphite-300);
}

.mega-menu__feature-text .text-link {
  font-size: 13px;
  margin-top: var(--space-2);
}

/* ---- Zone C: Utility icons ---- */

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

.site-header__utility .icon-btn {
  width: 24px;
  height: 24px;
}

.hamburger-btn {
  display: inline-flex;
}

@media (min-width: 1024px) {
  .hamburger-btn,
  .site-header__utility .icon-btn--search-mobile {
    display: none;
  }
}

/* ---------------------------------------------------------------------
   SEARCH OVERLAY
   --------------------------------------------------------------------- */

.search-overlay {
  position: fixed;
  inset: 0;
  z-index: var(--z-overlay);
  background: rgba(11, 13, 15, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-mid) var(--ease-out);
  padding-top: 120px;
}

.search-overlay.is-open {
  opacity: 1;
  pointer-events: auto;
}

.search-overlay__close {
  position: absolute;
  top: var(--space-6);
  right: var(--space-6);
  color: var(--color-white);
}

.search-overlay__inner {
  max-width: 640px;
  margin-inline: auto;
  padding-inline: var(--container-margin);
}

.search-overlay__field {
  position: relative;
  display: flex;
  align-items: center;
  height: 56px;
  border-bottom: 1px solid var(--color-graphite-border-dark);
  transition: border-color var(--dur-base) var(--ease-out);
}

.search-overlay__field:focus-within {
  border-color: var(--color-royal-violet);
}

.search-overlay__input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--color-white);
  font-family: var(--font-body);
  font-size: 18px;
  height: 100%;
}

.search-overlay__input::placeholder {
  color: var(--color-graphite-300);
}

.search-overlay__input:focus {
  outline: none;
}

.search-overlay__results {
  margin-top: var(--space-6);
}

.search-overlay__result {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding-block: var(--space-3);
  border-bottom: 1px solid var(--color-graphite-border-dark);
}

.search-overlay__result-thumb {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: var(--color-graphite-900);
  flex-shrink: 0;
}

.search-overlay__result-name {
  font-family: var(--font-body);
  font-size: 15px;
  color: var(--color-white);
}

.search-overlay__result-cas {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-graphite-300);
}

/* ---------------------------------------------------------------------
   MOBILE MENU
   --------------------------------------------------------------------- */

.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: var(--z-overlay);
  background: var(--color-obsidian);
  transform: translateX(100%);
  transition: transform var(--dur-mid) var(--ease-out-expo);
  overflow-y: auto;
  padding: var(--space-6);
}

.mobile-menu.is-open {
  transform: translateX(0);
}

.mobile-menu__header {
  display: flex;
  justify-content: flex-end;
  margin-bottom: var(--space-6);
}

.mobile-menu__close {
  color: var(--color-white);
}

.mobile-menu__search {
  width: 100%;
  height: 48px;
  background: var(--color-graphite-900);
  border: 1px solid var(--color-graphite-border-dark);
  border-radius: var(--radius-sm);
  padding-inline: var(--space-4);
  color: var(--color-white);
  font-family: var(--font-body);
  font-size: 15px;
  margin-bottom: var(--space-8);
}

.mobile-menu__search::placeholder {
  color: var(--color-graphite-300);
}

.mobile-menu__list {
  display: flex;
  flex-direction: column;
}

.mobile-menu__item {
  border-bottom: 1px solid var(--color-graphite-border-dark);
}

.mobile-menu__item-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: none;
  border: none;
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 28px;
  color: var(--color-white);
  padding-block: var(--space-6);
  text-align: left;
}

.mobile-menu__item-trigger .plus-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform var(--dur-base) var(--ease-out);
}

.mobile-menu__item.is-open .plus-icon {
  transform: rotate(45deg);
}

.mobile-menu__submenu {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--dur-mid) var(--ease-out);
}

.mobile-menu__item.is-open .mobile-menu__submenu {
  grid-template-rows: 1fr;
}

.mobile-menu__submenu-inner {
  overflow: hidden;
}

.mobile-menu__sublink {
  display: block;
  font-family: var(--font-body);
  font-size: 16px;
  color: var(--color-graphite-300);
  padding-block: var(--space-2);
  padding-left: var(--space-2);
}

.mobile-menu__footer {
  margin-top: var(--space-10);
  padding-bottom: var(--space-10);
}

.mobile-menu__account-link {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 15px;
  color: var(--color-white);
  background: none;
  border: none;
  padding: 0;
  text-align: left;
  cursor: pointer;
}

/* ---- Non-mega-menu simple links (For Institutions / About) ---- */
.primary-nav__link {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 14px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--color-white);
  position: relative;
  padding-block: var(--space-2);
}

.primary-nav__link--icon {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.primary-nav__link--icon svg {
  width: 15px;
  height: 15px;
  flex-shrink: 0;
  opacity: 0.85;
}

.primary-nav__item--dropdown {
  position: relative;
  display: inline-flex;
}

.primary-nav__item--dropdown .primary-nav__link {
  display: inline-flex;
  align-items: center;
}

.primary-nav__dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  margin-top: 0;
  padding-top: var(--space-3);
  min-width: 160px;
  opacity: 0;
  transform: translateY(4px);
  pointer-events: none;
  transition: opacity 160ms var(--ease-out), transform 160ms var(--ease-out);
  z-index: var(--z-dropdown);
}

.primary-nav__dropdown-inner {
  background: var(--color-white);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-modal);
  padding: var(--space-2);
}

.primary-nav__item--dropdown:hover .primary-nav__dropdown,
.primary-nav__item--dropdown:focus-within .primary-nav__dropdown {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.primary-nav__dropdown a {
  display: block;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 13px;
  text-transform: none;
  letter-spacing: normal;
  color: var(--color-obsidian);
  white-space: nowrap;
}

.primary-nav__dropdown a:hover {
  background: var(--color-cloud-grey);
  color: var(--color-royal-violet);
}

@media (max-width: 1023px) {
  .primary-nav__dropdown {
    display: none;
  }
}

.primary-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 100%;
  height: 1px;
  background: var(--color-royal-violet);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--dur-fast) var(--ease-out);
}

.primary-nav__link:hover::after,
.primary-nav__link:focus-visible::after {
  transform: scaleX(1);
}