/* =============================================================
 * layout.css — 导航 / 页脚 / 栅格系统
 * ============================================================= */

/* ---------------- 顶部导航 ---------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.78);
  backdrop-filter: saturate(180%) blur(18px);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--t) var(--ease), background var(--t) var(--ease),
    box-shadow var(--t) var(--ease);
}
.site-header.is-scrolled {
  border-bottom-color: var(--line);
  box-shadow: 0 4px 20px rgba(16, 32, 72, 0.06);
  background: rgba(255, 255, 255, 0.86);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.brand__logo {
  height: 34px;
  width: auto;
  max-width: 110px;
  object-fit: contain;
  display: block;
  border-radius: 6px;
}
.brand__mark {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: var(--brand-grad);
  display: grid;
  place-items: center;
  color: #fff;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  box-shadow: var(--sh-glow);
}
.brand__name { font-size: 1.05rem; }

.nav { display: flex; align-items: center; gap: 16px; flex-wrap: nowrap; }
.nav__link {
  position: relative;
  padding: 7px 10px;
  font-size: 17px;
  font-weight: 600;
  white-space: nowrap;
  color: var(--ink-2);
  border-radius: var(--r-pill);
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}
.nav__link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 4px;
  width: 22px;
  height: 2px;
  border-radius: 2px;
  background: var(--brand-grad);
  transform: translateX(-50%) scaleX(0);
  transition: transform var(--t) var(--ease);
}
.nav__link:hover { color: var(--ink); background: rgba(11, 18, 32, 0.04); }
.nav__link:hover::after,
.nav__link.is-active::after { transform: translateX(-50%) scaleX(1); }
.nav__link.is-active { color: var(--ink); font-weight: 700; }

.header-actions { display: flex; align-items: center; gap: 12px; }

/* 中英文切换 */
.lang-switch {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 34px;
  height: 34px;
  padding: 0 10px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--ink-2);
  border: 1px solid var(--line-strong);
  border-radius: 980px;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease),
    background var(--t-fast) var(--ease);
}
.lang-switch:hover { color: var(--brand); border-color: var(--brand); background: var(--bg-soft); }

/* 中宽屏：隐藏品牌副标题、收起冗余 CTA，保证导航一行不折行 */
@media (max-width: 1080px) {
  .brand__name { font-size: 1rem; }
}

/* 移动端汉堡 */
.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  position: relative;
}
.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  content: "";
  position: absolute;
  left: 12px;
  width: 20px;
  height: 2px;
  background: var(--ink);
  transition: transform var(--t) var(--ease), opacity var(--t-fast) var(--ease);
}
.nav-toggle span { top: 21px; }
.nav-toggle span::before { top: -6px; }
.nav-toggle span::after { top: 6px; }
body.nav-open .nav-toggle span { background: transparent; }
body.nav-open .nav-toggle span::before { transform: translateY(6px) rotate(45deg); }
body.nav-open .nav-toggle span::after { transform: translateY(-6px) rotate(-45deg); }

/* 移动端抽屉 */
@media (max-width: 900px) {
  .nav-toggle { display: block; }
  .nav {
    position: fixed;
    inset: var(--nav-h) 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 16px 20px 28px;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--sh-2);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--t) var(--ease), opacity var(--t) var(--ease);
  }
  body.nav-open .nav {
    transform: none;
    opacity: 1;
    pointer-events: auto;
  }
  .nav__link { padding: 14px 12px; font-size: 1rem; border-radius: 12px; }
  .nav__link::after { display: none; }
  .header-actions .btn--ghost { display: none; }
}

/* ---------------- 页脚 ---------------- */
.site-footer {
  background: var(--bg-dark);
  color: var(--on-dark-2);
  padding-block: var(--sp-7) var(--sp-4);
}
.site-footer a { color: var(--on-dark-2); transition: color var(--t-fast) var(--ease); }
.site-footer a:hover { color: #fff; }
/* 4 个链接列，桌面端一排显示不折行 */
.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--sp-4);
}
.footer-col h4 {
  color: #fff;
  font-size: var(--fs-sm);
  letter-spacing: 0.04em;
  margin-bottom: 16px;
}
.footer-col li { margin-bottom: 10px; font-size: var(--fs-sm); }
.footer-bottom {
  margin-top: var(--sp-6);
  padding-top: var(--sp-3);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: var(--fs-xs);
  color: var(--on-dark-2);
}
.footer-contact { display: grid; gap: 6px; font-size: var(--fs-sm); }

/* 备案与工商信息 */
.footer-legal {
  margin-top: var(--sp-4);
  padding-top: var(--sp-3);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: grid;
  gap: 8px;
  font-size: var(--fs-xs);
  color: var(--on-dark-3, #9aa6bd);
}
.footer-legal__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px 18px;
}
.footer-legal__sep { position: relative; padding-left: 18px; }
.footer-legal__sep::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 1px;
  height: 12px;
  background: rgba(255, 255, 255, 0.18);
  transform: translateY(-50%);
}
.footer-legal__sub { color: #8593ac; }

@media (max-width: 900px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--sp-4); }
}
@media (max-width: 560px) {
  .footer-grid { grid-template-columns: 1fr; }
}

/* ---------------- 通用栅格 ---------------- */
.grid { display: grid; gap: var(--sp-4); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* 两栏图文（编辑式） */
.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(32px, 6vw, 88px);
  align-items: center;
}
.split--reverse .split__media { order: 2; }
@media (max-width: 860px) {
  .split { grid-template-columns: 1fr; gap: var(--sp-4); }
  .split--reverse .split__media { order: 0; }
}

.stack > * + * { margin-top: var(--sp-3); }

/* ---------------- 导航项增至 8 个：中宽屏收紧间距，保证一行不折行 ---------------- */
@media (min-width: 901px) and (max-width: 1140px) {
  .nav { gap: 10px; }
  .nav__link { padding: 7px 8px; font-size: 16px; }
}
@media (min-width: 1141px) and (max-width: 1280px) {
  .nav { gap: 12px; }
  .nav__link { font-size: 16px; }
}