:nth-child() odd/even pseudo classes with definition list
<dl>
    <dt>green foo</dt>
    <dd>green bar</dd>
    <dt>red foo</dt>
    <dd>red bar</dd>
    <dt>green foo</dt>
    <dd>green bar</dd>
</dl>

<style>
dl { color: blue }
dd:nth-child(odd) { color:green }
dd:nth-child(even) { color:red }​
</style>

dd:nth-of-type(even) {color: red;}
dt:nth-of-type(even) {color: red;}
dd:nth-of-type(odd) {color: green;}
dt:nth-of-type(odd) {color: green;}