Showing required fields by bolding - html

Question

I have an HTML form. I would like to show that some of the fields are required by making them bold. In principle, should this go into the CSS rather than HTML? How would you do it?
<form action="doit" id="doit" method="post">
<label>
Name
<input id="name" name="name" type="text" />
</label>
<label>
Phone number
<input id="phone" name="phone" type="text" />
</label>
<label>
Year
<input id="year" name="year" type="text" />
</label>
</form>

Answer 1

Just of the top of my head, I think that if you're willing to use HTML5 and use the <input type="text" name="year" required> property, that you should be able to do:
input:required{
font-weight:bold;
}
And of course, you could go wild here and start throwing around borders and all sorts of stuff to make it really stand out.

Answer 2

Singularity's answer is perfectly valid. For the sake of completion, if you're not willing to use HTML5's required attribute, I would recommend adding a class by the same name to the inputs that are required.
<input type="text" name="firstname" class="required">
input.required {
font-weight: bold;
}
You can further use that class as a selector in your Javascript where you enforce the rule.
$(form).submit(function() {
$('input.required').each(function() {
if ($(this).val() === '') return false;
});
});
To answer the other question you were asking: the bold directive should go in CSS since it is purely presentational.