In the shown example, the last child element on the lists will be in bold. Then the CLASS in CSS looks like this:

LI:last-child {
font-weight: bold;
}

The code for the example looks like this:

<B>List 1:</B>
<UL>
<LI>Item 1</LI>
<LI>Item 2</LI>
<LI>Item 3</LI>
<LI>Item 4</LI>
<LI>Item 5</LI>
<LI>Item 6</LI>
</UL>

<B>List 2:</B>
<OL>
<LI>Item 1</LI>
<LI>Item 2</LI>
<LI>Item 3</LI>
<LI>Item 4</LI>
</OL>

On the screen, it looks like this:

List 1:

Item 1
Item 2
Item 3
Item 4
Item 5
Item 6

List 2:

Item 1
Item 2
Item 3
Item 4