/* =========================================================
   HEADER
========================================================= */

.site-header {
  --transition: 0.35s ease;

  position: fixed;
  inset: 0 0 auto;
  z-index: 1000;
  background:var(--fg);
  color:var(--bg);
  width: 100%;
  height: var(--header-height);
  border-bottom: 1px solid var(--border);
}

.site-header *,
.site-header *::before,
.site-header *::after {
  box-sizing: border-box;
}


/* =========================================================
   HEADER INNER
========================================================= */

.site-header .header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;

  width: 100%;
  max-width: var(--content-width);
  height: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
}


/* =========================================================
   SITE TITLE
========================================================= */

.site-header .site-title {
  position: relative;
  z-index: 1002;
  text-decoration: none;
}


/* =========================================================
   NAVIGATION
========================================================= */

.site-header nav > ul {
  display: flex;
  align-items: center;
  gap: 1.75rem;

  margin: 0;
  padding: 0;

  list-style: none;
}


/* Top-level items */

.site-header nav > ul > li {
  position: relative;
}


/* Links */

.site-header nav a {
  position: relative;

  display: block;
  text-decoration: none;
}


/* Underline */

.site-header nav > ul > li > a::after {
  position: absolute;
  inset-inline-start: 0;
  bottom: -0.375rem;
  background:var(--bg);
  width: 0;
  height: 2px;

  content: "";

  transition: width var(--transition);
}

.site-header nav > ul > li > a:hover::after,
.site-header nav > ul > li > a:focus-visible::after,
.site-header nav > ul > li.active > a::after {
  width: 100%;
}


/* =========================================================
   NESTED MENUS
========================================================= */

.site-header nav li > ul {
  position: absolute;
  inset-block-start: 100%;
  inset-inline-start: 0;

  min-width: 12rem;
  margin: 0;
  padding: 1rem 0;

  list-style: none;

  border: 1px solid var(--border);

  opacity: 0;
  visibility: hidden;
  transform: translateY(0.5rem);

  transition:
	opacity var(--transition),
	visibility 0s linear var(--transition),
	transform var(--transition);
}


/* Show child menu */

.site-header nav li:hover > ul,
.site-header nav li:focus-within > ul,
.site-header nav li.active > ul {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);

  transition:
	opacity var(--transition),
	visibility 0s,
	transform var(--transition);
}


/* Child links */

.site-header nav li > ul a {
  padding: 0.5rem 1rem;
  white-space: nowrap;
}


/* Nested active item */

.site-header nav li > ul li.active > a {
  font-weight: 700;
}


/* =========================================================
   SEARCH
========================================================= */

.site-header .search-wrapper {
  display: flex;
  align-items: center;
}

.site-header .search-wrapper .search-input {
  width: 0;
  margin: 0;
  padding: 0.375rem 0;

  border: 0;
  border-bottom: 1px solid currentColor;
  outline: 0;

  color: inherit;
  background: transparent;
  opacity: 0;

  transition:
	width var(--transition),
	opacity var(--transition),
	margin var(--transition);
}

.site-header .search-wrapper.active .search-input {
  width: 11.25rem;
  margin-inline-end: 0.75rem;
  opacity: 1;
}

.site-header .search-btn {
  display: flex;
  align-items: center;
  justify-content: center;

  width: 2.5rem;
  height: 2.5rem;
  padding: 0;

  border: 0;
  background: none;
  color: inherit;

  cursor: pointer;
}

.site-header .search-btn svg {
  width: 1.25rem;
  height: 1.25rem;
}


/* =========================================================
   HAMBURGER
========================================================= */

.site-header .menu-toggle {
  position: relative;
  z-index: 1002;

  display: none;
  align-items: center;
  justify-content: center;

  width: 2.625rem;
  height: 2.625rem;
  padding: 0;

  border: 0;
  background: none;
  color: inherit;

  cursor: pointer;
}

.site-header .menu-toggle span {
  position: absolute;

  width: 1.625rem;
  height: 0.125rem;

  background: currentColor;

  transition:
	transform var(--transition),
	opacity var(--transition);
}

.site-header .menu-toggle span:nth-child(1) {
  transform: translateY(-0.4375rem);
}

.site-header .menu-toggle span:nth-child(3) {
  transform: translateY(0.4375rem);
}


/* Hamburger → X */

.site-header.menu-open .menu-toggle span:nth-child(1) {
  transform: rotate(45deg);
}

.site-header.menu-open .menu-toggle span:nth-child(2) {
  opacity: 0;
}

.site-header.menu-open .menu-toggle span:nth-child(3) {
  transform: rotate(-45deg);
}


/* =========================================================
   MOBILE / TABLET
========================================================= */

@media (max-width: 56.25rem) {

  .site-header .menu-toggle {
	display: flex;
  }


  /* The menu: slides in from the right, below the header (site name and
     cross stay visible) */

  .site-header nav {
	position: fixed;
	inset: var(--header-height) 0 0;
	z-index: 1001;

	width: 100%;
	height: auto;

	display: flex;
	align-items: center;
	justify-content: center;

	background: var(--fg);
	color: var(--bg);

	transform: translateX(100%);
	visibility: hidden;

	transition:
	  transform 0.5s ease,
	  visibility 0s linear 0.5s;
  }

  .site-header nav.active {
	transform: translateX(0);
	visibility: visible;

	transition:
	  transform 0.5s ease,
	  visibility 0s;
  }


  /* Main list */

  .site-header nav > ul {
	flex-direction: column;
	align-items: center;

	gap: 2rem;

	width: 100%;
  }


  /* Main links: slide in when the menu opens */

  .site-header nav > ul > li > a {
	font-size: clamp(1.75rem, 6vw, 2rem);

	opacity: 0;
	transform: translateX(1.5rem);

	transition:
	  opacity var(--transition),
	  transform var(--transition);
  }

  .site-header nav.active > ul > li > a {
	opacity: 1;
	transform: translateX(0);
  }

  /* one after the other, 0.1 s apart (only when opening; closing is at once) */
  .site-header nav.active > ul > li:nth-child(1) > a { transition-delay: 0.2s; }
  .site-header nav.active > ul > li:nth-child(2) > a { transition-delay: 0.3s; }
  .site-header nav.active > ul > li:nth-child(3) > a { transition-delay: 0.4s; }
  .site-header nav.active > ul > li:nth-child(4) > a { transition-delay: 0.5s; }
  .site-header nav.active > ul > li:nth-child(5) > a { transition-delay: 0.6s; }
  .site-header nav.active > ul > li:nth-child(6) > a { transition-delay: 0.7s; }
  .site-header nav.active > ul > li:nth-child(n+7) > a { transition-delay: 0.8s; }


  /* Sub-menus: under their item, always open */

  .site-header nav li > ul {
	position: static;

	min-width: 0;
	padding: 0.5rem 0 0;

	border: 0;
	text-align: center;

	opacity: 1;
	visibility: visible;
	transform: none;
  }


  /* Buttons that stay on top of the open menu: hamburger/cross, search */

  .site-header .search-open,
  .site-header .search-btn {
	position: relative;
	z-index: 1002;
  }
}


/* The page behind the open menu does not scroll */

html.menu-open {
  overflow: hidden;
}


/* No sliding for visitors who turned animations off */

@media (prefers-reduced-motion: reduce) {
  .site-header *,
  .site-header *::before,
  .site-header *::after {
	transition: none !important;
  }
}