Glow Nav

<!-- Glow Nav — hover/active reveals an underline with a travelling spark -->
<nav class="nuda-ne2-nav" aria-label="Example">
  <a class="nuda-ne2-nav__link is-active" href="#">
    Home
    <span class="nuda-ne2-nav__spark" aria-hidden="true"></span>
  </a>
  <a class="nuda-ne2-nav__link" href="#">
    Work
    <span class="nuda-ne2-nav__spark" aria-hidden="true"></span>
  </a>
  <a class="nuda-ne2-nav__link" href="#">
    About
    <span class="nuda-ne2-nav__spark" aria-hidden="true"></span>
  </a>
</nav>

.nuda-ne2-nav {
  display: flex;
  gap: 24px;
  padding: 14px 18px;
  background: #0c0c10;
  border-radius: 10px;
}

.nuda-ne2-nav__link {
  position: relative;
  padding: 6px 2px;
  color: #cfcfcf;
  text-decoration: none;
  font-family: ui-sans-serif,system-ui,sans-serif;
  font-size: 14px;
  font-weight: 600;
  transition: color .25s ease;
}

.nuda-ne2-nav__link::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background: #e4ff54;
  box-shadow: 0 0 8px #e4ff54,0 0 16px rgba(228,255,84,.6);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .35s ease;
}

.nuda-ne2-nav__spark {
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 8px;
  height: 4px;
  border-radius: 2px;
  background: #fff;
  box-shadow: 0 0 8px #e4ff54,0 0 16px #e4ff54;
  opacity: 0;
}

.nuda-ne2-nav__link:hover,.nuda-ne2-nav__link:focus-visible,.nuda-ne2-nav__link.is-active {
  color: #fbffe0;
  outline: none;
}

.nuda-ne2-nav__link:hover::after,.nuda-ne2-nav__link:focus-visible::after,.nuda-ne2-nav__link.is-active::after {
  transform: scaleX(1);
}

.nuda-ne2-nav__link:hover .nuda-ne2-nav__spark,.nuda-ne2-nav__link:focus-visible .nuda-ne2-nav__spark,.nuda-ne2-nav__link.is-active .nuda-ne2-nav__spark {
  opacity: 1;
  animation: _nuda-ne2nav 1.1s linear infinite;
}

@keyframes _nuda-ne2nav {
  0% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(44px);
  }
}

@media (prefers-reduced-motion:reduce) {
  .nuda-ne2-nav__link,.nuda-ne2-nav__link::after {
    transition: none;
  }
  .nuda-ne2-nav__spark {
    animation: none;
    opacity: 0;
  }
}