/*
 * Shared Nihao World header.
 * Keep page-specific layout out of this file so every new top-level page can
 * use the same brand, navigation, About menu, and responsive ordering.
 */
.site-header {
  --teal-950: #123f43;
  --teal-800: #185b5c;
  --teal-100: #eaf5f2;
  --teal-50: #f4faf8;
  --ink-soft: #627879;
  --line: rgba(25, 91, 92, 0.14);
  position: sticky;
  z-index: 20;
  top: 0;
  display: grid;
  grid-template-columns: minmax(200px, 1fr) auto minmax(200px, 1fr);
  width: 100%;
  min-height: 82px;
  margin: 0;
  padding: 9px clamp(20px, 4.5vw, 72px);
  align-items: center;
  border: 0;
  border-bottom: 1px solid transparent;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
  backdrop-filter: none;
  transition: background-color 180ms ease, border-color 180ms ease, box-shadow 180ms ease;
}

.site-header.is-scrolled {
  border-bottom-color: rgba(25, 91, 92, 0.12);
  background: rgba(249, 252, 251, 0.92);
  box-shadow: 0 8px 24px rgba(19, 66, 67, 0.06);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  width: max-content;
  align-items: center;
  gap: 10px;
  color: var(--teal-950);
  text-decoration: none;
}

.brand img {
  width: 56px;
  height: 56px;
  object-fit: contain;
}

.brand-wordmark {
  display: inline-flex;
  align-items: baseline;
  white-space: nowrap;
}

.brand .brand-nihao,
.brand .brand-world {
  font-family: "Lora", Georgia, serif;
  font-size: 1.86rem;
  font-weight: 700;
  letter-spacing: -0.045em;
  line-height: 1;
}

.brand .brand-nihao {
  color: var(--teal-800);
  font-style: italic;
  font-weight: 700;
  letter-spacing: -0.035em;
  transform: scaleX(1.035);
  transform-origin: left center;
  -webkit-text-stroke: 0.32px currentColor;
}

.brand .brand-world {
  margin-left: 0.1em;
  color: #aa8247;
  font-style: normal;
}

.primary-nav {
  display: flex;
  align-items: center;
  justify-content: initial;
  gap: 4px;
}

.primary-nav a,
.about-menu > summary {
  border-radius: 6px;
  color: #335f60;
  font-size: 1.12rem;
  font-weight: 700;
  line-height: 1;
  text-decoration: none;
  transition: color 160ms ease, background 160ms ease, transform 160ms ease;
}

.primary-nav a {
  padding: 15px 22px;
  letter-spacing: -0.015em;
}

.primary-nav a:hover,
.primary-nav a.is-current {
  color: var(--teal-800);
  background: var(--teal-100);
}

.about-menu {
  position: relative;
  justify-self: end;
}

.about-menu > summary {
  padding: 11px 5px;
  border: 0;
  border-bottom: 1px solid rgba(25, 91, 92, 0.28);
  cursor: pointer;
  list-style: none;
}

.about-menu > summary::-webkit-details-marker {
  display: none;
}

.about-menu > summary:hover,
.about-menu[open] > summary {
  color: #fff;
  background: var(--teal-800);
  transform: translateY(-1px);
}

.about-popover {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  left: auto;
  display: grid;
  width: 300px;
  max-width: calc(100vw - 20px);
  padding: 7px;
  gap: 2px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
  box-shadow: 0 18px 46px rgba(19, 66, 67, 0.14);
}

.about-popover a {
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr);
  padding: 8px 9px;
  column-gap: 10px;
  row-gap: 1px;
  border-radius: 6px;
  color: var(--teal-950);
  text-decoration: none;
}

.about-popover a::before {
  content: "";
  display: grid;
  grid-column: 1;
  grid-row: 1 / span 2;
  width: 36px;
  height: 36px;
  place-items: center;
  align-self: center;
  border-radius: 10px;
  background-position: center;
  background-repeat: no-repeat;
  background-size: 22px 22px;
}

.about-popover a:nth-child(1)::before {
  background-color: #8b75aa;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Ccircle cx='12' cy='8' r='3'/%3E%3Cpath d='M5.5 20a6.5 6.5 0 0 1 13 0'/%3E%3C/svg%3E");
}

.about-popover a:nth-child(2)::before {
  background-color: #6f91b4;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M5 3h9l4 4v5M5 3v18h7M14 3v5h4'/%3E%3Ccircle cx='16.5' cy='16.5' r='3.5'/%3E%3Cpath d='m19 19 2 2'/%3E%3C/svg%3E");
}

.about-popover a:nth-child(3)::before {
  background-color: #d99832;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M4 5h16v11H9l-5 4zM8 9h8M8 12h5'/%3E%3C/svg%3E");
}

.about-popover a:nth-child(4)::before {
  background-color: #568b72;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M12 3l7 3v5c0 4.6-2.9 8.1-7 10-4.1-1.9-7-5.4-7-10V6z'/%3E%3Cpath d='m8.5 12 2.2 2.2 4.8-5'/%3E%3C/svg%3E");
}

.about-popover a:hover {
  background: var(--teal-50);
}

.about-popover strong {
  display: block;
  grid-column: 2;
  font-size: 0.9rem;
  line-height: 1.25;
}

.about-popover small {
  display: block;
  grid-column: 2;
  color: var(--ink-soft);
  font-size: 0.73rem;
  line-height: 1.35;
}

.menu-toggle {
  position: relative;
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
  transition: background-color 160ms ease;
}

.menu-toggle:hover {
  background: rgba(234, 245, 242, 0.72);
}

.menu-toggle:focus-visible {
  outline: 2px solid rgba(37, 117, 114, 0.48);
  outline-offset: 2px;
}

.menu-toggle span {
  position: absolute;
  left: 10px;
  display: block;
  width: 24px;
  height: 2px;
  margin: 0;
  border-radius: 2px;
  background: var(--teal-800);
  transition: top 180ms ease, opacity 140ms ease, transform 180ms ease;
}

.menu-toggle span:nth-child(1) {
  top: 13px;
}

.menu-toggle span:nth-child(2) {
  top: 21px;
}

.menu-toggle span:nth-child(3) {
  top: 29px;
}

.culture-mobile-return {
  display: none;
}

.menu-toggle[aria-expanded="true"] span:nth-child(1) {
  top: 21px;
  transform: rotate(45deg);
}

.menu-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0.35);
}

.menu-toggle[aria-expanded="true"] span:nth-child(3) {
  top: 21px;
  transform: rotate(-45deg);
}

@media (max-width: 900px) {
  .site-header {
    grid-template-columns: 1fr auto auto;
  }

  .menu-toggle {
    display: grid;
    grid-column: 3;
  }

  .about-menu {
    grid-column: 2;
    grid-row: 1;
    margin-right: 8px;
  }

  .primary-nav {
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    display: none;
    width: min(280px, calc(100vw - 32px));
    padding: 8px;
    align-items: stretch;
    flex-direction: column;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: #fff;
    box-shadow: 0 20px 54px rgba(19, 66, 67, 0.09);
  }

  .primary-nav.is-open {
    display: flex;
  }

  .primary-nav a {
    display: grid;
    grid-template-columns: 52px minmax(0, 1fr);
    min-height: 64px;
    padding: 6px 12px;
    align-items: center;
    gap: 12px;
  }

  .primary-nav a::before {
    content: "";
    display: block;
    width: 52px;
    height: 52px;
    border: 1px solid rgba(25, 91, 92, 0.1);
    border-radius: 10px;
    background-color: #f8fbfa;
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
  }

  .primary-nav a[href*="learn.html"]::before {
    background-image: url("assets/brand/homepage-learn-chinese-card-v3.webp");
  }

  .primary-nav a[href*="books.html"]::before {
    background-image: url("assets/brand/homepage-textbook-card-v4.webp");
  }

  .primary-nav a[href*="culture.html"]::before {
    background-image: url("assets/brand/homepage-culture-card-v4.webp");
  }
}

@media (max-width: 650px) {
  .site-header {
    width: 100%;
    min-height: 68px;
    margin: 0;
    padding: 8px 10px;
    border-radius: 0;
  }

  .brand img {
    width: 46px;
    height: 46px;
  }

  .brand .brand-nihao,
  .brand .brand-world {
    font-size: 1.48rem;
  }

  .menu-toggle {
    grid-column: 3;
  }
}

@media (max-width: 900px) {
  .culture-story-header {
    grid-template-columns: minmax(0, 1fr) auto auto auto;
    column-gap: 10px;
  }

  .culture-story-header .culture-mobile-return {
    display: inline-flex;
    grid-column: 2;
    grid-row: 1;
    min-height: 44px;
    padding: 0 3px;
    align-items: center;
    justify-content: center;
    border: 0;
    border-bottom: 1px solid rgba(37, 117, 114, 0.34);
    border-radius: 0;
    color: var(--teal-800);
    background: transparent;
    font-size: 0.875rem;
    font-weight: 700;
    line-height: 1;
    text-decoration: none;
    white-space: nowrap;
  }

  .culture-story-header .culture-mobile-return:hover,
  .culture-story-header .culture-mobile-return:focus-visible {
    border-color: var(--teal-800);
    color: var(--teal-950);
    background: transparent;
  }

  .culture-story-header .about-menu {
    grid-column: 3;
  }

  .culture-story-header .menu-toggle {
    grid-column: 4;
  }
}

@media (max-width: 650px) {
  .culture-story-header {
    grid-template-columns: minmax(0, 1fr) auto auto;
    grid-template-rows: auto auto;
    column-gap: 8px;
    row-gap: 2px;
  }

  .culture-story-header .culture-mobile-return {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-self: start;
    min-height: 38px;
  }

  .culture-story-header .about-menu {
    grid-column: 2;
    grid-row: 1;
    margin-right: 0;
  }

  .culture-story-header .menu-toggle {
    grid-column: 3;
    grid-row: 1;
  }
}

@media (max-width: 520px) {
  .culture-story-header .brand-wordmark {
    display: none;
  }
}