<nav class="radikalwp-nav-underline"><a class="radikalwp-nav-underline-link" href="#">دوره‌ها<//a><a class="radikalwp-nav-underline-link is-active" href="#">مقالات<//a><a class="radikalwp-nav-underline-link" href="#">دانلودها<//a><a class="radikalwp-nav-underline-link" href="#">درباره ما<//a><//nav>

.radikalwp-nav-underline {
  display: flex;
  gap: 30px;
}
.radikalwp-nav-underline-link {
  position: relative;
  padding: 8px 2px;
  font-size: 14px;
  font-weight: 700;
  color: #334155;
  text-decoration: none;
  transition: color .25s ease;
}
.radikalwp-nav-underline-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  right: 50%;
  width: 0;
  height: 2.5px;
  border-radius: 999px;
  background: #4f46e5;
  transform: translateX(50%);
  transition: width .3s cubic-bezier(.25, .8, .3, 1);
}
.radikalwp-nav-underline-link:hover { color: #4f46e5; }
.radikalwp-nav-underline-link:hover::after,
.radikalwp-nav-underline-link.is-active::after { width: 100%; }
.radikalwp-nav-underline-link.is-active { color: #4f46e5; }