[philja]

I don't think float can take the value 'center'. But you can achieve the result you want by putting the line concerned in a <p> with a class defined as 'center' and then within that <p>, using spans to float your words left or right.

For example:

<p class="center"><span style="float:left">lorem</span>ipsum <span style="float:right">dolor</span></p>

where the CSS stylesheet defines:

p.center {text-align: center;}

Or use a table, as Karellen suggests.