/* ============================================
   YIFU Layout
   Header / Footer / Mega Menu / Drawer / Search Overlay
   ============================================ */

/* ========== Site Header ========== */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  height: var(--header-height);
  background-color: rgba(251, 250, 248, 0.96);
  border-bottom: 1px solid transparent;
  transition: background-color var(--motion-base) var(--easing),
              border-color var(--motion-base) var(--easing),
              backdrop-filter var(--motion-base) var(--easing);
}

.site-header.is-scrolled {
  background-color: rgba(251, 250, 248, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom-color: rgba(37, 37, 37, 0.06);
}

.header-inner {
  width: var(--container-width);
  height: 100%;
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-8);
}

/* Logo */
.site-logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  height: 100%;
}

.site-logo img {
  height: 38px;
  width: auto;
  object-fit: contain;
}

/* Desktop Nav */
.desktop-nav {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  flex: 1;
  justify-content: center;
  /* 统一 Mega Menu 定位上下文（3.6.2）：作为 .mega-menu 的最近定位祖先，
     使所有栏目弹层以同一容器中心对齐，左/右/宽度/顶部Y 一致。 */
  position: relative;
}

.desktop-nav__item {
  /* 取消每项独立定位上下文（3.6.2）：弹层改由 .desktop-nav 统一定位。
     .desktop-nav__link 已是 position:relative，下划线 ::after 不受影响。 */
  position: static;
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.desktop-nav__link {
  font-size: 0.9375rem;
  color: var(--color-text);
  padding: var(--space-2) 0;
  position: relative;
  transition: color var(--motion-fast) var(--easing);
  letter-spacing: 0.02em;
}

.desktop-nav__link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--color-champagne);
  transition: width var(--motion-base) var(--easing);
}

.desktop-nav__link:hover,
.desktop-nav__item.is-active .desktop-nav__link {
  color: var(--color-text);
}

.desktop-nav__item.is-active .desktop-nav__link::after,
.desktop-nav__link:hover::after {
  width: 100%;
}

/* Header Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-shrink: 0;
}

.header-search-btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2);
  font-size: 0.9375rem;
  color: var(--color-text);
  min-width: 44px;
  min-height: 44px;
  justify-content: center;
  transition: color var(--motion-fast) var(--easing);
}

.header-search-btn:hover {
  color: var(--color-champagne);
}

.header-search-btn svg {
  width: 20px;
  height: 20px;
}

.header-purchase-btn {
  display: inline-flex;
  align-items: center;
  padding: 10px 24px;
  font-size: 0.875rem;
  border: 1px solid var(--color-text);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  transition: all var(--motion-base) var(--easing);
  min-height: 40px;
}

.header-purchase-btn:hover {
  background-color: var(--color-text);
  color: var(--color-ivory);
}

/* Mobile Menu Button */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 0;
}

.mobile-menu-btn span {
  display: block;
  width: 22px;
  height: 1.5px;
  background-color: var(--color-text);
  transition: transform var(--motion-base) var(--easing),
              opacity var(--motion-base) var(--easing);
}

/* ========== Mega Menu ========== */
.mega-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  width: min(100vw - 48px, 860px);
  background-color: var(--color-ivory);
  border-top: 1px solid var(--color-warm-gray);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.08);
  padding: var(--space-12) var(--space-10);
  /* 统一最小高度（3.6.2）：内容少的栏目（如真实口碑仅 2 项）不再塌陷。
     按 tokens 估算 padding(var(--space-12)*2=96) + 约 3 行内容(~160) ≈ 256px。 */
  min-height: 256px;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--motion-base) var(--easing),
              transform var(--motion-base) var(--easing),
              visibility var(--motion-base) var(--easing);
  z-index: var(--z-mega);
}

.desktop-nav__item:hover .mega-menu,
.desktop-nav__item:focus-within .mega-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.mega-menu__grid {
  display: grid;
  /* 统一三列（3.6.2）：minmax(0,1fr) 防止长标题撑破列宽，等宽三列。 */
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-12) var(--space-10);
}

.mega-menu__col-title {
  font-family: var(--font-en);
  font-size: var(--fs-eyebrow);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-champagne);
  margin-bottom: var(--space-4);
}

.mega-menu__links {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.mega-menu__link {
  font-size: 0.9375rem;
  color: var(--color-text);
  transition: color var(--motion-fast) var(--easing);
  padding: 2px 0;
}

.mega-menu__link:hover {
  color: var(--color-champagne);
}

.mega-menu__link-desc {
  display: block;
  font-size: var(--fs-small);
  color: var(--color-tertiary);
  margin-top: 2px;
}

/* ========== Mobile Drawer ========== */
.mobile-drawer {
  position: fixed;
  inset: 0;
  z-index: var(--z-drawer);
  background-color: var(--color-ivory);
  transform: translateX(100%);
  transition: transform var(--motion-base) var(--easing);
  overflow-y: auto;
  visibility: hidden;
}

.mobile-drawer.is-open {
  transform: translateX(0);
  visibility: visible;
}

.mobile-drawer__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-6);
  height: var(--header-height-mobile);
  border-bottom: 1px solid var(--color-warm-gray);
  position: sticky;
  top: 0;
  background-color: var(--color-ivory);
  z-index: 1;
}

.mobile-drawer__close {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--color-text);
}

.mobile-drawer__nav {
  padding: var(--space-6);
}

.mobile-nav-item {
  border-bottom: 1px solid var(--color-warm-gray);
}

.mobile-nav-item__toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) 0;
  font-family: var(--font-serif);
  font-size: 1.35rem;
  color: var(--color-text);
  min-height: 52px;
}

.mobile-nav-item__toggle-icon {
  font-family: var(--font-en);
  font-size: 1.25rem;
  color: var(--color-tertiary);
  transition: transform var(--motion-base) var(--easing);
  flex-shrink: 0;
  width: 24px;
  text-align: center;
}

.mobile-nav-item.is-open .mobile-nav-item__toggle-icon {
  transform: rotate(45deg);
}

.mobile-nav-item__submenu {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--motion-base) var(--easing);
}

.mobile-nav-item.is-open .mobile-nav-item__submenu {
  max-height: 400px;
}

.mobile-nav-item__sublinks {
  padding-bottom: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.mobile-nav-item__sublink {
  font-size: 1rem;
  color: var(--color-muted);
  padding: var(--space-2) 0;
  min-height: 44px;
  display: flex;
  align-items: center;
}

.mobile-nav-item__sublink:hover {
  color: var(--color-champagne);
}

.mobile-drawer__footer {
  padding: var(--space-6);
  border-top: 1px solid var(--color-warm-gray);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.mobile-drawer__footer-link {
  font-size: 1rem;
  color: var(--color-text);
  padding: var(--space-2) 0;
  min-height: 44px;
  display: flex;
  align-items: center;
}

/* Drawer Overlay */
.drawer-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(37, 37, 37, 0.4);
  z-index: calc(var(--z-drawer) - 1);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--motion-base) var(--easing),
              visibility var(--motion-base) var(--easing);
}

.drawer-overlay.is-visible {
  opacity: 1;
  visibility: visible;
}

/* ========== Search Overlay ========== */
.search-overlay {
  position: fixed;
  inset: 0;
  z-index: var(--z-search);
  background-color: rgba(251, 250, 248, 0.98);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--motion-base) var(--easing),
              visibility var(--motion-base) var(--easing);
  overflow-y: auto;
}

.search-overlay.is-open {
  opacity: 1;
  visibility: visible;
}

.search-overlay__inner {
  width: var(--container-width);
  margin-inline: auto;
  padding-top: var(--space-16);
  padding-bottom: var(--space-16);
}

.search-overlay__close {
  position: absolute;
  top: var(--space-6);
  right: var(--space-6);
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--color-text);
}

.search-overlay__label {
  font-family: var(--font-en);
  font-size: var(--fs-eyebrow);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-champagne);
  margin-bottom: var(--space-4);
}

.search-overlay__input-wrap {
  position: relative;
  margin-bottom: var(--space-12);
}

.search-overlay__input {
  width: 100%;
  padding: var(--space-4) 0;
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 3vw, 2.5rem);
  background: none;
  border: none;
  border-bottom: 2px solid var(--color-warm-gray);
  color: var(--color-text);
  transition: border-color var(--motion-fast) var(--easing);
}

.search-overlay__input:focus {
  outline: none;
  border-bottom-color: var(--color-champagne);
}

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

.search-overlay__suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.search-overlay__suggestion-label {
  font-size: var(--fs-small);
  color: var(--color-tertiary);
  margin-bottom: var(--space-4);
  width: 100%;
}

/* ========== Site Footer ========== */
.site-footer {
  background-color: var(--footer-bg);
  color: var(--footer-text);
  padding-top: var(--space-24);
  padding-bottom: var(--space-8);
}

.footer-inner {
  width: var(--container-width);
  margin-inline: auto;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.5fr repeat(4, 1fr);
  gap: var(--space-12);
  padding-bottom: var(--space-16);
  border-bottom: 1px solid var(--footer-border);
}

.footer-brand__logo {
  margin-bottom: var(--space-4);
}

.footer-brand__logo img {
  height: 36px;
  width: auto;
  filter: brightness(0) invert(1);
  opacity: 0.9;
}

.footer-brand__tagline {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  color: var(--footer-muted);
  margin-bottom: var(--space-6);
  line-height: 1.7;
}

.footer-col__title {
  font-family: var(--font-en);
  font-size: var(--fs-eyebrow);
  font-weight: 300;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--footer-text);
  margin-bottom: var(--space-6);
}

.footer-col__links {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.footer-col__link {
  font-size: 0.9375rem;
  color: var(--footer-muted);
  padding: 2px 0;
  transition: color var(--motion-fast) var(--easing);
  min-height: 32px;
  display: inline-flex;
  align-items: center;
}

.footer-col__link:hover {
  color: var(--footer-text);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-8);
  flex-wrap: wrap;
  gap: var(--space-4);
}

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

.footer-legal__link {
  font-size: var(--fs-small);
  color: var(--footer-muted);
  transition: color var(--motion-fast) var(--easing);
}

.footer-legal__link:hover {
  color: var(--footer-text);
}

.footer-copyright {
  font-size: var(--fs-small);
  color: var(--footer-muted);
  font-family: var(--font-en);
}

/* ========== Page Hero ========== */
.page-hero {
  padding-top: var(--space-16);
  padding-bottom: var(--space-16);
  background: var(--gradient-hero);
}

.page-hero--science {
  background: var(--gradient-science);
}

.page-hero__inner {
  width: var(--container-width);
  margin-inline: auto;
}

/* Home hero: two-column editorial layout */
.page-hero__grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: var(--space-12);
  align-items: center;
}

.page-hero__media {
  aspect-ratio: 4 / 5;
  border-radius: var(--radius-lg, 20px);
  overflow: hidden;
}

.page-hero__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.page-hero__eyebrow {
  font-family: var(--font-en);
  font-size: var(--fs-eyebrow);
  font-weight: 300;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-champagne);
  margin-bottom: var(--space-4);
}

.page-hero__title {
  font-size: var(--fs-h1);
  line-height: var(--lh-tight);
  margin-bottom: var(--space-6);
  max-width: 800px;
}

.page-hero--service .page-hero__title {
  font-size: clamp(2.6rem, 4.4vw, 4.4rem);
}

/* 产品详情页 Hero：PC 左文右图 */
@media (min-width: 1024px) {
  .page-hero--product .page-hero__inner > .reveal {
    position: relative;
    display: grid;
    grid-template-columns: 1.05fr 0.95fr;
    column-gap: var(--space-10);
    row-gap: 0;
    align-content: start;
    align-items: start;
    margin-top: var(--space-8);
  }
  .page-hero--product .page-hero__desc {
    margin-bottom: var(--space-7);
  }
  .page-hero--product .page-hero__inner > .reveal .page-hero__eyebrow,
  .page-hero--product .page-hero__inner > .reveal .page-hero__title,
  .page-hero--product .page-hero__inner > .reveal .page-hero__desc,
  .page-hero--product .page-hero__inner > .reveal > p:not(.page-hero__eyebrow):not(.page-hero__desc),
  .page-hero--product .page-hero__inner > .reveal > div:last-child {
    grid-column: 1;
  }
  .page-hero--product .page-hero__meta {
  margin-top: var(--space-6);
  color: var(--color-muted);
  font-size: var(--fs-sm);
  line-height: 1.5;
}

.page-hero--product .page-hero__media {
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 340px;
    max-width: 340px;
    margin: 0;
  }
}

.page-hero--product .page-hero__title {
  font-size: clamp(2.6rem, 5vw, 4.4rem);
}

.page-hero__desc {
  font-size: var(--fs-body-lg);
  color: var(--color-muted);
  line-height: var(--lh-body-lg);
  max-width: 640px;
}

/* ========== Content Block ========== */
.content-block {
  padding-block: var(--section-gap);
}

.content-block--mist {
  background-color: var(--color-mist);
}

.prose {
  max-width: var(--container-reading);
  margin-inline: auto;
}

.prose h2 {
  font-size: clamp(1.6rem, 2.5vw, 2.2rem);
  margin-top: var(--space-12);
  margin-bottom: var(--space-4);
}

.prose h3 {
  font-size: 1.3rem;
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
}

.prose p {
  margin-bottom: var(--space-6);
  color: var(--color-text);
  line-height: var(--lh-body);
}

.prose ul,
.prose ol {
  margin-bottom: var(--space-6);
  padding-left: var(--space-6);
}

.prose ul {
  list-style: disc;
}

.prose ol {
  list-style: decimal;
}

.prose li {
  margin-bottom: var(--space-2);
  color: var(--color-text);
  line-height: 1.8;
}

.prose blockquote {
  border-left: 2px solid var(--color-champagne);
  padding-left: var(--space-6);
  margin: var(--space-8) 0;
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--color-muted);
  line-height: 1.8;
}