/* ============================================================
   QINGNENG V2 — Responsive
   ============================================================ */

@media (max-width:1024px){
  .process-track{grid-template-columns:repeat(2,1fr)}
  .process-item{padding-right:26px}
  .portfolio{grid-template-columns:1fr}
  .p-item,.p-item.wide{min-height:440px;grid-column:span 1}
  .safety-grid{grid-template-columns:1fr 1fr}
  .cert-grid{grid-template-columns:1fr 1fr}
  .scene-strip{grid-template-columns:1fr 1fr 1fr}
  .footer-grid{grid-template-columns:1fr 1fr}
  .quote-grid,.oem-grid{grid-template-columns:1fr}
  .stage-grid{grid-template-columns:1fr;gap:20px}
  .stage-copy{order:2}
  .stage-prod{min-height:380px;order:1}
  .about-split{grid-template-columns:1fr}
}

@media (max-width:860px){
  .nav-links{
    position:fixed;inset:var(--nav-h) 0 auto 0;z-index:99;
    flex-direction:column;align-items:stretch;gap:0;
    background:rgba(7,11,17,.96);border-bottom:1px solid var(--line);
    padding:12px 24px 20px;
    transform:translateY(-16px);opacity:0;visibility:hidden;
    transition:transform .3s var(--ease),opacity .3s,visibility .3s;
    -webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);
  }
  .nav-links.open{transform:none;opacity:1;visibility:visible}
  .nav-links a{padding:14px 6px;font-size:.92rem;border-bottom:1px solid var(--line)}
  .nav-toggle{display:flex}
  .nav .btn--quote{display:none}
  .nav-links .btn{width:100%;justify-content:center;margin-top:10px}
  .hero-grid{grid-template-columns:1fr;gap:20px}
  .hero{min-height:auto;padding-top:calc(var(--nav-h) + 30px)}
  .hero-visual{order:2;margin-top:10px}
  .hero-stage{min-height:400px}
  .hero-product{width:min(330px,80vw)}
  .hero-meta{grid-template-columns:repeat(3,1fr);gap:12px}
  .hero-scroll{display:none}
}

@media (max-width:640px){
  .container{width:calc(100% - 36px)}
  .hero-meta{grid-template-columns:1fr;gap:16px;border-top:0;padding-top:0;margin-top:30px}
  .hero-meta>div{padding-top:16px;border-top:1px solid var(--line)}
  .process-track{grid-template-columns:1fr}
  .safety-grid,.cert-grid{grid-template-columns:1fr}
  .scene-strip{grid-template-columns:1fr}
  .scene{height:300px}
  .footer-grid{grid-template-columns:1fr;gap:30px}
  .form{grid-template-columns:1fr}
  .form .full,.form .submit,.form-ok,.form-note{grid-column:span 1}
  .oem-list{grid-template-columns:1fr}
  .hero-tag.t1{left:-2%;top:6%}
  .hero-tag.t2{right:-2%}
  .hero-tag.t3{left:0;bottom:-2%}
  .hero-tag{max-width:170px;padding:10px 13px}
  .stage-prod{min-height:300px}
  .stage-sticky{height:100vh;padding:90px 0 40px}
  .sys-item .tag{position:static;display:inline-block;margin-left:8px;vertical-align:middle}
}

@media (max-width:420px){
  .nav-logo .t{font-size:.92rem}
  .hero h1{font-size:2.15rem}
  .hero-tag.t2{display:none}
}