change font-weight on hover

.c-main-navigation__menu > li > a,
.sub-menu > li > a {
  display: block;
  text-transform: uppercase;
  position: relative;
  transition: all 0.2s;

  &:after {
    background-image: none;
    display: block;
    content: attr(link-title);
    font-weight: 700;
    height: 1px;
    overflow: hidden;
    visibility: visible;
    position: relative;
  }

  &:hover {
    font-weight: 700;
  }
}

link-title (Titel des Links) muss als Attribut auf dem Element vorhanden sein.

<a href="https://www.alea.co.at/personalvermittlung/" link-title="Personalvermittlung"><span><img width="150" height="150" src="https://www.alea.co.at/wp-content/uploads/2019/05/alea_pro-150x150.png" class="attachment-thumbnail size-thumbnail" alt=""></span>Personalvermittlung</a>