Best way I came across doing is like this:
HTML5:
<p>Initial Colors <a id="new-color">Different Colors</a></p>
CSS3:
p {
color: #000000;
text-decoration-line: underline;
text-decoration-color: #a11015;
}
p #new-color{
color: #a11015;
text-decoration-line: underline;
text-decoration-color: #000000;
}