Links (<a href="#">...</a>) in a page should definitely stand out from regular text. The implementation of a different color as well as underlines for hyperlinks pronounces a feeling of external linkage. This is a fair use of CSS styling, as long as the colour of the link is not the ugly default blue.

The color is styled. But notice how the color of the underline is also styled to the color of the text? It may seem consistant for a design to have its links the same colors, but the purpose of the underline is to emphasize the text of the link, not the underline itself as it’s technically not part of the link. You’ll notice the color of the underlines of the links on this site are slightly lighter than the actual link color. This will effectively visually isolate the link but not make a big deal out of it.

The technical part of this effect is to use CSS to get rid of the underline (yes, get rid of it), and add a border to the bottom of the link. For example:

a {
    color: #000066;
    text-decoration: none;
    border-bottom: 1px solid #bfbfc8;
}

Of course, a nice hover effect would conclude this nicely. A brighter text color and darker underline should do it.

a:hover {
    color: #000099;
    text-decoration: none;
    border-bottom: 1px solid #a6a6b2;
}

And that’s it!