Sub Category Images not aligned

Hi All, I'm not sure if this is a new topic or old but I'm having a problem with my opencart. I have created a few subcategory under one category and under those are category, some have longer names and some shorter. The problem I'm having is that they are "sometimes" not aligned as shown in the picture.

http://www.free1d.com/opencart/image/Free1dnotalign.png

can anyone help?

thanks all!