Target first level <li>s and not the nested <li>s

I have the following HTML:

<ul>
  <li>A
    <ul>
      <li>subsection</li>
    </ul>
  </li>
  <li>B
    <ul>
      <li>subsection</li>
    </ul>
  </li>
  <li>C
    <ul>
      <li>subsection</li>
    </ul>
  </li>
</ul>

With jQuery, how do I target the FIRST level of <li>s?

For example, I need to make the font bold on hover to the <li>s with the letters A, B and C, but NOT have that font style applied to the nested <li>s (with the name subsections).

Here's an initial jsfiddle DEMO if you'd like to use it.

Thanks.

EDIT--

Solution:

CHILD SELECTORS, that's the answer.

No need for jQuery, this can be done using CSS.

Here's the updated DEMO

EDIT-- Here's a more clear demo

Thanks,