/* =========================================================
   框架布局 layout.css —— 顶部导航 / 下拉菜单 / 页脚 / 返回顶部
   ========================================================= */

/* ---------- 顶部导航 ---------- */
.site-header {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  height: var(--header-h);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: box-shadow var(--dur) var(--ease), border-color var(--dur) var(--ease),
              background-color var(--dur) var(--ease);
}
.site-header.scrolled { box-shadow: 0 2px 16px rgba(16, 42, 86, 0.08); border-bottom-color: var(--c-line); }

.nav-wrap { display: flex; align-items: center; height: 100%; gap: var(--sp-6); }

/* Logo 区 */
.brand { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.brand svg { height: 38px; width: auto; }
.brand-name { font-size: 19px; font-weight: 700; letter-spacing: 1px; color: var(--c-ink); }
.brand-name em { font-style: normal; color: var(--c-primary); }
.brand-slogan { font-size: 10px; color: var(--c-ink-4); letter-spacing: 2px; margin-top: -3px; }

/* 主菜单 */
.nav-menu { display: flex; align-items: center; height: 100%; margin-left: auto; }
.nav-item { position: relative; height: 100%; }
.nav-link {
  display: flex; align-items: center; gap: 5px; height: 100%;
  padding: 0 16px; font-size: 15px; font-weight: 500; color: var(--c-ink-2);
  position: relative; transition: color var(--dur) var(--ease);
}
.nav-link::after {
  content: ""; position: absolute; left: 16px; right: 16px; bottom: 0;
  height: 3px; border-radius: 3px 3px 0 0;
  background: linear-gradient(90deg, var(--c-primary-light), var(--c-primary));
  transform: scaleX(0); transform-origin: center;
  transition: transform var(--dur) var(--ease);
}
.nav-link:hover { color: var(--c-primary); }
.nav-item.active .nav-link { color: var(--c-primary); font-weight: 600; }
.nav-item.active .nav-link::after,
.nav-item:hover .nav-link::after { transform: scaleX(1); }
.nav-link .caret { width: 10px; height: 10px; transition: transform var(--dur) var(--ease); }
.nav-item:hover .caret { transform: rotate(180deg); }

/* 下拉面板 */
.dropdown {
  position: absolute; top: calc(100% - 6px); left: 50%;
  transform: translate(-50%, 8px);
  min-width: 168px; padding: var(--sp-2);
  background: #fff; border: 1px solid var(--c-line); border-radius: var(--r-m);
  box-shadow: var(--sh-3);
  opacity: 0; visibility: hidden; pointer-events: none;
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease), visibility var(--dur);
}
.nav-item:hover .dropdown,
.nav-item:focus-within .dropdown { opacity: 1; visibility: visible; pointer-events: auto; transform: translate(-50%, 0); }
.dropdown a {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 12px; border-radius: var(--r-s);
  font-size: 14px; color: var(--c-ink-2);
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease);
}
.dropdown a:hover { background: var(--c-bg-soft); color: var(--c-primary); }
.dropdown a .dd-icon {
  display: grid; place-items: center; width: 26px; height: 26px; flex-shrink: 0;
  border-radius: var(--r-s); background: rgba(22, 104, 220, 0.1); color: var(--c-primary);
}
.dropdown a .dd-icon svg { width: 14px; height: 14px; }
.dropdown a .dd-sub { display: block; font-size: var(--fs-mini); color: var(--c-ink-4); line-height: 1.3; }

/* 导航右侧动作 */
.nav-actions { display: flex; align-items: center; gap: var(--sp-3); flex-shrink: 0; }
.nav-tel { display: flex; align-items: center; gap: 6px; font-size: var(--fs-small); color: var(--c-ink-3); }
.nav-tel strong { color: var(--c-primary-deep); font-size: 15px; font-family: var(--font-num); letter-spacing: 0.5px; }

/* 汉堡按钮（移动端） */
.hamburger { display: none; width: 40px; height: 40px; border-radius: var(--r-s); position: relative; }
.hamburger span {
  position: absolute; left: 9px; right: 9px; height: 2px; border-radius: 2px;
  background: var(--c-ink); transition: all var(--dur) var(--ease);
}
.hamburger span:nth-child(1) { top: 13px; }
.hamburger span:nth-child(2) { top: 19px; }
.hamburger span:nth-child(3) { top: 25px; }
.hamburger.open span:nth-child(1) { top: 19px; transform: rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { top: 19px; transform: rotate(-45deg); }

/* 移动端抽屉 */
.mobile-drawer {
  position: fixed; top: var(--header-h); left: 0; right: 0; z-index: 99;
  background: #fff; border-bottom: 1px solid var(--c-line); box-shadow: var(--sh-3);
  padding: var(--sp-4) var(--sp-5) var(--sp-6);
  max-height: calc(100dvh - var(--header-h)); overflow-y: auto;
  transform: translateY(-12px); opacity: 0; visibility: hidden;
  transition: all var(--dur) var(--ease);
}
.mobile-drawer.open { transform: none; opacity: 1; visibility: visible; }
.mobile-drawer .m-link { display: block; padding: 13px 4px; font-size: 16px; font-weight: 500; border-bottom: 1px dashed var(--c-line); }
.mobile-drawer .m-link.active { color: var(--c-primary); }
.mobile-drawer .m-group-title { margin: var(--sp-4) 0 var(--sp-2); font-size: var(--fs-mini); color: var(--c-ink-4); letter-spacing: 2px; }
.mobile-drawer .m-sub { display: flex; align-items: center; gap: 8px; padding: 10px 4px 10px 16px; font-size: 14px; color: var(--c-ink-2); border-bottom: 1px dashed var(--c-line); }
.mobile-drawer .m-sub::before { content: ""; width: 5px; height: 5px; border-radius: 50%; background: var(--c-primary-light); }
.mobile-drawer .m-tel { margin-top: var(--sp-5); text-align: center; color: var(--c-ink-3); font-size: var(--fs-small); }
.mobile-drawer .m-tel strong { display: block; font-size: 22px; color: var(--c-primary-deep); font-family: var(--font-num); }

@media (max-width: 1024px) {
  .nav-menu, .nav-actions .nav-tel { display: none; }
  .hamburger { display: block; }
  .nav-wrap { justify-content: space-between; }
}

/* ---------- 页脚 ---------- */
.site-footer { background: linear-gradient(180deg, #103a7d, var(--c-bg-deep)); color: rgba(255,255,255,0.72); position: relative; overflow: hidden; }
.site-footer::before {
  content: ""; position: absolute; top: -40%; right: -8%; width: 420px; height: 420px;
  border-radius: 50%; background: radial-gradient(circle, rgba(64,150,255,0.25), transparent 70%);
  pointer-events: none;
}
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1.2fr; gap: var(--sp-7); padding: var(--sp-8) 0 var(--sp-7); position: relative; }
.footer-brand .brand-name { color: #fff; }
.footer-brand p { margin-top: var(--sp-4); font-size: var(--fs-small); line-height: 1.9; }
.footer-col h4 { font-size: 15px; color: #fff; margin-bottom: var(--sp-4); font-weight: 600; }
.footer-col a, .footer-col span { display: block; font-size: var(--fs-small); padding: 5px 0; transition: color var(--dur); }
.footer-col a:hover { color: #fff; }
.footer-col .soon { color: rgba(255,255,255,0.4); }
.footer-col .soon::after { content: "建设中"; font-size: 10px; margin-left: 6px; padding: 2px 6px; border-radius: 4px; background: rgba(255,255,255,0.12); }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.12); padding: var(--sp-4) 0; display: flex; flex-wrap: wrap; gap: var(--sp-3); justify-content: space-between; font-size: var(--fs-mini); color: rgba(255,255,255,0.45); position: relative; }
.footer-bottom a:hover { color: #fff; }

@media (max-width: 1024px) { .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--sp-6); } }
@media (max-width: 640px) { .footer-grid { grid-template-columns: 1fr; } }

/* ---------- 返回顶部 ---------- */
.back-top {
  position: fixed; right: 26px; bottom: 30px; z-index: 90;
  width: 46px; height: 46px; border-radius: 50%;
  display: grid; place-items: center;
  background: #fff; color: var(--c-primary); box-shadow: var(--sh-3);
  border: 1px solid var(--c-line);
  opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: all var(--dur) var(--ease);
}
.back-top.show { opacity: 1; visibility: visible; transform: none; }
.back-top:hover { background: var(--c-primary); color: #fff; border-color: var(--c-primary); }
.back-top svg { width: 18px; height: 18px; }