.main a:not(.button) {
  color: #48719D;
  text-decoration: none;
  border-bottom: 1px solid currentColor;
}

.main a:not(.button):hover {
  border-bottom-width: 2px;
}

.footer a {
  color: #8FB3D9; /* helles Blau, sehr gut lesbar */
  text-decoration: none;
  border-bottom: 2px solid transparent;
}

.footer p a {
  display: inline-block;      /* damit padding wirkt */
  padding: 10px 0;            /* erhöht Touch-Höhe */
  line-height: 1.2;
}

.footer p a + br {
  display: block;
  content: "";
  margin-bottom: 2px;         /* optional, Abstand zwischen Links */
}