p {text-decoration: underline;}
.ex1 {text-decoration-style: solid;}
.ex2 {text-decoration-style: double;}
.ex3 {text-decoration-style: dotted;}
.ex4 {text-decoration-style: dashed;}
.ex5 {text-decoration-style: wavy;}
<!DOCTYPE html>
<html lang="ko">
<head></head>
<body>
<h1>text-decoration-style</h1>
<p class="ex1">This is solid.</p>
<p class="ex2">This is double.</p>
<p class="ex3">This is dotted.</p>
<p class="ex4">This is dashed.</p>
<p class="ex5">This is wavy.</p>
</body>
</html>