I occasionally have to add a class to an html element based on a condition. The problem is I can't figure out a clean way of doing it. Here's an example of the stuff I've tried:

<div <%= if @status = 'success'; "class='ok'"; end %>>
   some message here
</div>

OR

<% if @status == 'success' %>
   <div class='success'>
<% else %>
   <div>
<% end %>
   some message here
</div>

I don't like the first approach because it's crowded looking and hard to read. I don't like the second approach because the nesting is screwed up. It'd be nice to put it in the model, (something like @status.css_class), but that doesn't belong there. What do most people do?