/* Robotics Reviewed: Research submenu in the site header (Nov 2, 2026). Separate from rr.css (WD-owned) until WD folds it in. */
.nav-dd{position:relative;display:flex;align-items:center}
.nav-dd>a{padding-right:6px}
.nav-dd-btn{display:inline-flex;align-items:center;justify-content:center;width:26px;height:32px;margin-left:-2px;padding:0;border:0;border-radius:var(--r-pill);background:none;color:var(--on-ink-muted);cursor:pointer}
.nav-dd-btn:hover,.nav-dd-btn[aria-expanded="true"]{color:#fff;background:var(--ink-3)}
.nav-dd-btn svg{width:12px;height:12px;transition:transform .2s var(--ease)}
.nav-dd-btn[aria-expanded="true"] svg{transform:rotate(180deg)}
.nav-dd-menu{position:absolute;top:calc(100% + 8px);left:0;min-width:200px;display:none;flex-direction:column;gap:2px;padding:8px;background:var(--ink-2);border:1px solid var(--ink-line);border-radius:var(--r-2);box-shadow:0 18px 40px -12px rgba(0,0,0,.6);z-index:60}
.nav-dd-menu::before{content:"";position:absolute;left:0;right:0;top:-10px;height:10px}
.nav-dd-menu a{display:block;padding:10px 12px;border-radius:var(--r-1);white-space:nowrap}
.nav-dd-menu a[aria-current="page"]::after{display:none}
.nav-dd:hover .nav-dd-menu,.nav-dd:focus-within .nav-dd-menu,.nav-dd.open .nav-dd-menu{display:flex}
@media (max-width:980px){
  .nav-dd{flex-direction:column;align-items:stretch}
  .nav-dd>a{padding-right:8px}
  .nav-dd-btn{display:none}
  .nav-dd-menu,.nav-dd:hover .nav-dd-menu{position:static;display:flex;min-width:0;padding:0 0 4px 16px;background:none;border:0;box-shadow:none}
  .nav-dd-menu::before{display:none}
  .nav-dd-menu a{font-size:var(--fs-16);padding:8px 8px;color:var(--on-ink-muted)}
}
@media (prefers-reduced-motion:reduce){.nav-dd-btn svg{transition:none}}