/* ===================================================================
   layout.css — 吸顶导航 / 移动抽屉 / 页脚 / 栅格 / 响应式
   =================================================================== */

/* ---------- 吸顶导航 Header ---------- */
.header {
  position: sticky; top: 0; z-index: 100; height: var(--header-h);
  background: rgba(255,255,255,.92); backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--border); transition: box-shadow .3s, background .3s;
}
.header.scrolled { box-shadow: 0 4px 20px rgba(22,50,79,.1); }
.header__inner { height: 100%; display: flex; align-items: center; justify-content: space-between; }
.logo { display: flex; align-items: center; gap: 10px; }
.logo img { height: 38px; width: auto; }
.logo__text { font-weight: 800; font-size: 19px; color: var(--navy); letter-spacing: .5px; }
.logo__text small { display: block; font-size: 11px; font-weight: 500; color: var(--text-soft); letter-spacing: 2px; }

.nav { display: flex; align-items: center; gap: 4px; height: 100%; }
.nav__item { position: relative; height: 100%; display: flex; align-items: center; }
.nav__link {
  display: flex; align-items: center; gap: 5px; padding: 0 16px; height: 100%;
  font-size: 15px; font-weight: 600; color: var(--text); transition: color .2s; position: relative;
}
.nav__link::after {
  content: ""; position: absolute; left: 16px; right: 16px; bottom: 14px; height: 2px;
  background: var(--accent); transform: scaleX(0); transform-origin: left; transition: transform .25s var(--ease);
}
.nav__item:hover .nav__link, .nav__link.active { color: var(--navy); }
.nav__item:hover .nav__link::after, .nav__link.active::after { transform: scaleX(1); }

/* 关于我们 下拉子菜单 */
.nav__dropdown {
  position: absolute; top: var(--header-h); left: 0; min-width: 220px;
  background: #fff; border: 1px solid var(--border); border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  box-shadow: var(--shadow); padding: 8px 0; opacity: 0; visibility: hidden;
  transform: translateY(8px); transition: all .22s var(--ease);
}
.nav__item:hover .nav__dropdown { opacity: 1; visibility: visible; transform: translateY(0); }
.nav__dropdown a {
  display: block; padding: 10px 20px; font-size: 14px; font-weight: 500; color: var(--text-soft);
  transition: all .18s;
}
.nav__dropdown a:hover { background: var(--bg-soft); color: var(--accent); padding-left: 26px; }

/* 语言切换 + 汉堡 */
.header__actions { display: flex; align-items: center; gap: 14px; }
.lang-switch {
  display: inline-flex; border: 1px solid var(--border); border-radius: 999px; overflow: hidden;
}
.lang-switch button { padding: 6px 12px; font-size: 13px; font-weight: 600; color: var(--text-soft); transition: all .2s; }
.lang-switch button.active { background: var(--navy); color: #fff; }
.hamburger { display: none; width: 26px; height: 20px; position: relative; }
.hamburger span { position: absolute; left: 0; width: 100%; height: 2px; background: var(--navy); border-radius: 2px; transition: all .3s; }
.hamburger span:nth-child(1) { top: 0; }
.hamburger span:nth-child(2) { top: 9px; }
.hamburger span:nth-child(3) { top: 18px; }
.hamburger.open span:nth-child(1) { top: 9px; transform: rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { top: 9px; transform: rotate(-45deg); }

/* 移动端抽屉 */
.drawer {
  position: fixed; top: var(--header-h); left: 0; right: 0; bottom: 0; z-index: 99;
  background: #fff; padding: 16px 24px 40px; overflow-y: auto;
  transform: translateX(100%); transition: transform .3s var(--ease); display: none;
}
.drawer.open { transform: translateX(0); }
.drawer__link { display: block; padding: 15px 4px; font-size: 17px; font-weight: 600; color: var(--text); border-bottom: 1px solid var(--border); }
.drawer__sub { display: none; padding: 6px 0 10px 14px; }
.drawer__sub.open { display: block; }
.drawer__toggle::after { content: "▾"; margin-left: 6px; font-size: 12px; }
.caret { margin-left: 4px; font-size: 11px; color: var(--text-soft); }
.drawer__sub a { display: block; padding: 9px 0; font-size: 15px; color: var(--text-soft); }
.drawer__lang { margin-top: 20px; display: flex; gap: 10px; }

/* ---------- 页脚 ---------- */
.footer { background: var(--bg-deep); color: #c4d2e0; padding: 60px 0 26px; font-size: 14px; }
.footer__grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1.2fr; gap: 36px; }
.footer__brand .logo__text { color: #fff; }
.footer__brand p { color: #9fb1c4; margin-top: 14px; max-width: 320px; }
.footer__col h4 { color: #fff; font-size: 15px; margin-bottom: 16px; }
.footer__col a { display: block; padding: 7px 0; color: #9fb1c4; transition: color .2s; }
.footer__col a:hover { color: var(--accent-2); }
.footer__contact p { margin: 6px 0; color: #9fb1c4; }
.footer__contact strong { color: #fff; }
.footer__bottom {
  border-top: 1px solid rgba(255,255,255,.1); margin-top: 40px; padding-top: 22px;
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; color: #8aa0b6; font-size: 13px;
}
.footer__bottom .lang-switch button { color: #9fb1c4; }
.footer__bottom .lang-switch button.active { color: #fff; }

/* ---------- 栅格 ---------- */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-5 { grid-template-columns: repeat(5, 1fr); }

/* ---------- 响应式 ---------- */
@media (max-width: 960px) {
  .nav { display: none; }
  .hamburger { display: block; }
  .drawer { display: block; }
  .footer__grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 760px) {
  .section { padding: 52px 0; }
  .grid-3, .grid-4, .grid-5 { grid-template-columns: repeat(2, 1fr); }
  .grid-2 { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .grid-3, .grid-4, .grid-5 { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; }
  .container { padding: 0 18px; }
}