How do I assign a css class based on spry data?

Question

I need to assign a css class based on the value of spry data. IOW - I need to do a calculation on two values and assign a class to that <tr> if the resulting value if > 0. Is it possible to plug spry data into php? Is there a better way to go about doing this? Spry may have a function that will hide or style data based on the value of that data, but I can't find it.

Answer 1

I think I need to provide better information. I currently have:
<tbody spry:repeatchildren="JSCC_Courses" spry:choose="choose" >  
                        <tr spry:when="'{method}' == 'WEB'" style="background-color: #fffdc7;">                                       
                            <td>{callno}</td>
                            <td>{rubric}</td>
                            <td>{session}</td>
                            <td>{hours}</td>
                            <td>{title}</td>
                            <td>{days}</td>
                            <td>{time}</td>
                            <td>{room}</td>
                            <td>{instructor}</td>
                            <td>{seats}</td>
                            <td>{location}</td>
                          </tr>
                         <tr spry:when="'{method}' == 'VDC'" style="background-color: #cbffc7;" >                                       
                            <td>{callno}</td>
                            <td>{rubric}</td>
                            <td>{session}</td>
                            <td>{hours}</td>
                            <td>{title}</td>
                            <td>{days}</td>
                            <td>{time}</td>
                            <td>{room}</td>
                            <td>{instructor}</td>
                            <td>{seats}</td>
                            <td>{location}</td>
                          </tr>
                       <tr spry:default="default">                                       
                            <td>{callno}</td>
                            <td>{rubric}</td>
                            <td>{session}</td>
                            <td>{hours}</td>
                            <td>{title}</td>
                           <td>{days}</td>
                            <td>{time}</td>
                            <td>{room}</td>
                            <td>{instructor}</td>
                            <td>{seats}</td>
                            <td>{location}</td>
                         </tr>
</tbody>
I now need to add a class to the <tr> if the {seats} > 0. I'm having trouble conceptualizing how this works in conjunction with my current spry:whens.