<div>Еще <span class="wavytext">один пример</span> в CSS.</div>
div { font-size: 55px; line-height: 55px}
.wavytext {
  text-decoration: underline;
  -webkit-text-decoration-style: wavy;
  text-decoration-style: wavy;
  -webkit-text-decoration-color: darkslateblue;
  text-decoration-color: darkslateblue;  
}
Rerun