/* ==========================================================
   站点公共顶部浮动导航栏
   被 index.html / 404.html 共同引用，改这里两页同时生效
   ========================================================== */

:root{
  --brand:#2563eb;
  --brand-2:#1e40af;
  --brand-soft:#eff4ff;
  --accent:#ff7a18;
  --accent-2:#ff9d4d;
  --ink:#0f172a;
  --muted:#64748b;
  --line:#e8edf5;
  --soft:#f7f9fd;
  --shadow-sm:0 2px 8px rgba(15,23,42,.05);
}

.container{max-width:1200px;margin:0 auto;padding:0 24px}

/* ---------- 导航主体 ---------- */
.nav{
  position:sticky;top:0;z-index:100;flex:none;
  background:rgba(255,255,255,.86);
  -webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);
  border-bottom:1px solid transparent;transition:border-color .3s,box-shadow .3s;
}
.nav.scrolled{border-bottom-color:var(--line);box-shadow:var(--shadow-sm)}
.nav-inner{display:flex;align-items:center;height:68px;gap:40px}

.brand{display:flex;align-items:center;gap:11px;font-size:19px;font-weight:800;letter-spacing:.5px}
.brand .mark{
  width:36px;height:36px;border-radius:10px;flex:none;
  background:linear-gradient(135deg,var(--brand) 0%,#4f8bff 100%);
  display:flex;align-items:center;justify-content:center;color:#fff;
  font-size:17px;font-weight:700;box-shadow:0 6px 16px rgba(37,99,235,.32);
}
.nav-links{display:flex;gap:32px;margin-left:8px}
.nav-links a{font-size:15px;color:#475569;font-weight:500;transition:color .2s}
.nav-links a:hover{color:var(--brand)}
.nav-cta{margin-left:auto;display:flex;align-items:center;gap:14px}

/* ---------- 导航按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:11px 24px;border-radius:999px;font-size:15px;font-weight:600;
  cursor:pointer;border:none;transition:all .25s;white-space:nowrap;
}
.btn-primary{
  background:linear-gradient(135deg,var(--accent) 0%,var(--accent-2) 100%);
  color:#fff;box-shadow:0 8px 20px rgba(255,122,24,.28);
}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 12px 28px rgba(255,122,24,.36)}
.btn-sm{padding:9px 20px;font-size:14px}

/* ---------- 汉堡按钮（仅窄屏显示） ---------- */
.nav-toggle{
  display:none;width:42px;height:42px;flex:none;cursor:pointer;
  border:none;border-radius:12px;background:var(--brand-soft);
  flex-direction:column;align-items:center;justify-content:center;gap:5px;
}
.nav-toggle span{display:block;width:18px;height:2px;border-radius:2px;background:var(--brand);transition:all .28s}
.nav-toggle[aria-expanded="true"] span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] span:nth-child(2){opacity:0;transform:scaleX(.4)}
.nav-toggle[aria-expanded="true"] span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}

/* ---------- 移动端下拉菜单 ---------- */
.nav-menu{
  display:none;flex-direction:column;background:#fff;overflow:hidden;
  max-height:0;transition:max-height .32s ease;
}
.nav-menu.open{max-height:340px;border-top:1px solid var(--line)}
.nav-menu a{
  padding:14px 24px;font-size:15.5px;font-weight:600;color:#334155;
  border-bottom:1px solid #f1f5f9;
}
.nav-menu a:last-child{border-bottom:none}
.nav-menu a:active{background:var(--soft)}

/* ---------- 响应式 ---------- */
@media (max-width:980px){
  .container{padding:0 20px}
  .nav-links{display:none}
  .nav-toggle{display:flex}
  .nav-menu{display:flex}
}
@media (max-width:768px){
  .container{
    padding-left:max(18px,env(safe-area-inset-left));
    padding-right:max(18px,env(safe-area-inset-right));
  }
}
@media (max-width:560px){
  .nav-inner{height:60px;gap:12px}
  .nav .brand{font-size:17px}
  .nav .brand .mark{width:32px;height:32px;font-size:15px;border-radius:9px}
  .nav-cta{gap:10px}
  .nav-cta .btn-primary{padding:8px 16px;font-size:13.5px}
}

/* 触屏：去掉会粘滞的位移 */
@media (hover:none){
  .btn-primary:hover{transform:none}
}