.mobile-nav-toggle,
.mobile-nav-only { display: none; }

.mobile-nav-toggle {
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: transparent;
  cursor: pointer;
}
.mobile-nav-toggle-lines { display: grid; gap: 4px; }
.mobile-nav-toggle-line {
  display: block;
  width: 18px;
  height: 1px;
  margin-inline: auto;
  background: currentColor;
  transition: transform .2s ease, opacity .2s ease;
}
.mobile-nav-toggle[aria-expanded='true'] .mobile-nav-toggle-line:nth-child(1) { transform: translateY(5px) rotate(45deg); }
.mobile-nav-toggle[aria-expanded='true'] .mobile-nav-toggle-line:nth-child(2) { opacity: 0; }
.mobile-nav-toggle[aria-expanded='true'] .mobile-nav-toggle-line:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }

@media (max-width: 900px) {
  nav .nav-inner { position: relative; }
  .mobile-nav-toggle { display: grid; place-content: center; flex: 0 0 44px; }
  nav .nav-links {
    position: fixed;
    z-index: -1;
    inset: 0;
    width: 100%;
    height: 100dvh;
    min-height: 100vh;
    margin: 0;
    padding: 110px 20px 28px;
    overflow-y: auto;
    overscroll-behavior: contain;
    display: none;
    align-items: stretch;
    flex-direction: column;
    gap: 0;
    background: var(--bg);
  }
  nav .nav-links.is-open { display: flex; }
  nav .nav-links::before {
    margin-bottom: 24px;
    color: var(--muted);
    content: 'Explore AI2SEE';
    font: 500 12px/1.4 var(--f-sans);
    letter-spacing: .04em;
  }
  nav .nav-links > li,
  nav .nav-links > li.mobile-nav-only { display: block; width: 100%; }
  nav .nav-links li + li { border-top: 1px solid var(--line-soft); }
  nav .nav-links a,
  nav .nav-links a.nav-cta {
    width: 100%;
    min-height: 64px;
    justify-content: space-between;
    padding: 12px 0;
    border-radius: 0;
    background: transparent;
    color: var(--ink);
    font-size: clamp(24px, 7vw, 34px) !important;
    font-weight: 500 !important;
    letter-spacing: -.035em;
  }
  nav .nav-links a::after { right: auto; bottom: 10px; left: 0; width: 54px; transform-origin: left; }
  nav .nav-links a:hover::after,
  nav .nav-links a.active::after,
  nav .nav-links a:focus-visible::after { transform: scaleX(1); }
  nav .nav-links a.nav-cta { margin-top: 0; }
  nav .nav-links a.nav-cta::before { color: var(--accent); content: '↗'; font: 500 24px/1 var(--f-sans); order: 2; }
  nav .nav-links .mobile-nav-only a { min-height: 48px; color: var(--muted); font-size: 18px !important; }
}

@media (prefers-reduced-motion: reduce) {
  .mobile-nav-toggle-line { transition: none; }
}

/* Navigation remains available when scripting is disabled or fails. */
@media (max-width: 900px) {
  html:not(.nav-ready) nav { position: relative; background: var(--bg); }
  html:not(.nav-ready) nav .nav-inner { height: auto; flex-wrap: wrap; padding-block: 18px; }
  html:not(.nav-ready) .mobile-nav-toggle { display: none; }
  html:not(.nav-ready) nav .nav-links { display: flex; position: static; height: auto; min-height: 0; padding: 16px 0 0; z-index: auto; }
  html:not(.nav-ready) nav .nav-links::before { display: none; }
  html:not(.nav-ready) nav .nav-links a { min-height: 44px; font-size: 18px !important; }
}

.mobile-nav-toggle {
  border-radius: 100px;
  gap: 4px;
  transition: background 180ms var(--ease-out), border-color 180ms var(--ease-out);
}
@media (hover: hover) and (pointer: fine) {
  .mobile-nav-toggle:hover { background: var(--surface); }
}