/* Vùng liên hệ dành sẵn từ lần vẽ đầu; hình học 3D đọc chiều cao .thanh-goi. */
:root{--cao-thanh-lh:0px}
.thanh-goi.thanh-lh{display:none}
@media(max-width:759px){
  :root{--cao-thanh-lh:calc(72px + env(safe-area-inset-bottom,0px))}
  html body{padding-bottom:var(--cao-thanh-lh)}
  .thanh-goi.thanh-lh{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));align-items:center;gap:8px;position:fixed;left:0;right:0;bottom:0;z-index:61;box-sizing:border-box;height:var(--cao-thanh-lh);padding:11px 12px calc(12px + env(safe-area-inset-bottom,0px));background:#fff;border-top:1px solid #E1E6EE}
  .thanh-goi.thanh-lh .nut{display:flex;align-items:center;justify-content:center;box-sizing:border-box;min-width:0;min-height:48px;margin:0;padding:0 4px;border:1px solid #E1E6EE;border-radius:6px;background:#fff;color:#122442;font:inherit;font-size:13px;font-weight:500;line-height:1.3;text-align:center;text-decoration:none;white-space:nowrap}
  .thanh-goi.thanh-lh .nut-navy{background:#122442;border-color:#122442;color:#fff}
  .thanh-goi.thanh-lh .nut:focus-visible{outline:2px solid #122442;outline-offset:2px}
}