[Zope] tal:attributes question

I have this: style="position:absolute;left:180;top:25;z-index:1;visibility:hidden;" I need to make 'top' change after each iteration. So, I have a little python operation called position that will return a new value and I want to make 'top' contain that value. My tal:attributes... looks like this => tal:attributes="id string:${box}" I was thinking about tweaking the tal:attributes to include 'style' <div tal:attributes="id string:${box}; style string:position:absolute;left:180;top:${position};z-index:1;visibility:h idden;"> Of course, this won't work merely because of all the semicolons. Does anyone have an idea of how I would go about this? Maybe my approach is not the best way. Thank You, Laura