/* ============================================================
   AICOR 官网 · 组件：完整导航 Nav
   ------------------------------------------------------------
   适用于带「联系方式 + 下拉 + 二维码 + CTA」的完整导航。
   页面：index / reports / more-cases / about / services / case /
         join / methodology / organization / reports/* / cases/*
   依赖：tokens.css、utilities.css（.container）
   简化导航（news/article）见 nav-simple.css
   ============================================================ */

/* ---------- 顶栏骨架 ---------- */
header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  padding: 22px 0;
  transition: all 0.35s ease;
  border-bottom: 1px solid transparent;
}
header.scrolled {
  padding: 14px 0;
  background: rgba(4,6,12,0.82);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom-color: var(--line-soft);
}
.nav-wrap { display: flex; align-items: center; justify-content: space-between; }

/* ---------- 品牌 ---------- */
.nav-logo { display: flex; align-items: center; gap: 14px; }
.nav-logo img { height: 26px; }
.nav-logo .nav-brand-cn { font-size: 13px; color: var(--text-3); letter-spacing: 2px; border-left: 1px solid var(--line); padding-left: 14px; }

/* ---------- 主导航 ---------- */
nav { display: flex; gap: 38px; align-items: center; }
nav a { font-size: 14px; color: var(--text-2); letter-spacing: 1px; transition: color 0.2s; position: relative; }
nav a:hover { color: var(--text-1); }
nav a::after { content: ""; position: absolute; left: 0; bottom: -6px; width: 0; height: 1px; background: var(--grad); transition: width 0.25s; }
nav a:hover::after { width: 100%; }
nav a.active { color: var(--text-1); font-weight: 600; }
nav a.active::after { width: 100%; height: 2px; box-shadow: 0 0 8px rgba(79,140,255,0.6); }

/* ---------- 导航 CTA ---------- */
.nav-cta {
  padding: 9px 22px; border: 1px solid rgba(255,255,255,0.22); border-radius: 100px;
  font-size: 13px; letter-spacing: 2px; color: var(--text-1) !important;
  transition: all 0.25s;
}
.nav-cta::after { display: none; }
.nav-cta:hover { border-color: transparent; background: var(--grad); box-shadow: 0 4px 24px rgba(79,140,255,0.35); }

/* ---------- 右区：联系方式 ---------- */
.nav-right { display: flex; align-items: center; gap: 26px; }
.nav-contact { display: flex; align-items: center; gap: 12px; }
.nav-contact-item, .nav-contact .nav-wechat {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 12.5px; letter-spacing: 0.5px; color: var(--text-2);
  white-space: nowrap; transition: color 0.2s;
}
.nav-contact-item:hover, .nav-contact .nav-wechat:hover { color: var(--text-1); }
.nav-contact-item svg, .nav-contact .nav-wechat svg { width: 13px; height: 13px; flex: none; opacity: 0.75; }
.nav-contact-item:hover svg, .nav-contact .nav-wechat:hover svg { opacity: 1; }
.nav-contact-line { width: 1px; height: 14px; background: var(--line); }
@media (max-width: 1080px) { .nav-contact { display: none; } }

/* ---------- 下拉菜单 ---------- */
.nav-drop { position: relative; }
.nav-drop-link { display: inline-flex; align-items: center; gap: 4px; }
.nav-drop-link .caret { display: inline-flex; align-items: center; opacity: 0.85; margin-left: 2px; transition: transform 0.25s; color: var(--text-2); }
.nav-drop:hover .caret, .nav-drop.open .caret { transform: rotate(180deg); }
.nav-drop-menu {
  position: absolute; top: calc(100% + 14px); left: 50%; transform: translate(-50%, 8px);
  background: #0d1626; border: 1px solid var(--line); border-radius: 12px; padding: 7px;
  min-width: 128px; display: flex; flex-direction: column; gap: 2px;
  opacity: 0; visibility: hidden; transition: all 0.22s ease;
  z-index: 300; box-shadow: 0 18px 50px rgba(0,0,0,0.45);
}
.nav-drop-menu::before { content: ""; position: absolute; top: -14px; left: 0; right: 0; height: 14px; }
.nav-drop-menu a { padding: 9px 18px; font-size: 13px; border-radius: 8px; white-space: nowrap; text-align: center; }
.nav-drop-menu a::after { display: none; }
.nav-drop-menu a:hover { color: var(--text-1); background: rgba(255,255,255,0.05); }
.nav-drop-menu a.active { color: var(--text-1); font-weight: 600; }
.nav-drop:hover .nav-drop-menu, .nav-drop.open .nav-drop-menu, .nav-drop:focus-within .nav-drop-menu {
  opacity: 1; visibility: visible; transform: translate(-50%, 0);
}
@media (max-width: 1080px) {
  .nav-drop-menu {
    position: static; transform: none; opacity: 1; visibility: visible; display: none;
    flex-direction: column; background: transparent; border: none; box-shadow: none;
    padding: 0 0 0 12px; min-width: 0;
  }
  .nav-drop.open .nav-drop-menu { display: flex; }
  .nav-drop-menu a { text-align: left; padding: 6px 4px; }
}

/* ---------- 导航二维码 ---------- */
.nav-qr { position: relative; display: inline-flex; align-items: center; gap: 8px; }
.nav-qr-thumb { width: 20px; height: 20px; border-radius: 5px; cursor: pointer; border: 1px solid var(--line); background: #fff; }
.nav-qr-label { font-size: 12px; color: var(--text-2); letter-spacing: 0.5px; white-space: nowrap; transition: color 0.2s; }
.nav-qr:hover .nav-qr-label { color: var(--text-1); }
.nav-qr-pop {
  position: absolute; top: calc(100% + 16px); right: -6px;
  background: #0d1626; border: 1px solid var(--line); border-radius: 14px;
  padding: 14px 14px 12px; display: flex; flex-direction: column; align-items: center; gap: 9px;
  opacity: 0; visibility: hidden; transform: translateY(8px); transition: all 0.25s ease;
  z-index: 300; box-shadow: 0 18px 50px rgba(0,0,0,0.5);
}
.nav-qr-pop::before { content: ""; position: absolute; top: -14px; left: 0; right: 0; height: 14px; }
.nav-qr-pop img { width: 148px; height: 148px; max-width: none; border-radius: 10px; background: #fff; padding: 7px; box-sizing: content-box; object-fit: contain; }
.nav-qr-pop span { font-size: 12px; color: var(--text-2); letter-spacing: 3px; }
.nav-qr:hover .nav-qr-pop { opacity: 1; visibility: visible; transform: translateY(0); }

/* ---------- 语言切换器（下拉框：中/英/西） ---------- */
.nav-lang { display: inline-flex; align-items: center; margin-left: 16px; padding-left: 16px; border-left: 1px solid var(--line); }
.lang-select { font-size: 12px; color: var(--text-1); font-family: inherit; letter-spacing: 0.5px; padding: 4px 8px; border: 1px solid var(--line); border-radius: 6px; background: transparent; cursor: pointer; outline: none; transition: all 0.2s; appearance: auto; }
.lang-select:hover { border-color: var(--accent); color: var(--accent); }
.lang-select option { color: #1a1a2e; background: #fff; }
@media (max-width: 1080px) { .nav-lang { margin-left: 0; padding-left: 0; border-left: none; } }