Append this css:
ul.wjecf-cols > li {
box-sizing: border-box;
text-align: center;
}
The box-sizing fixes an issue with the column width (I will include this in the next release).
The text-align centers the radio-button and title above the image. It still looks a bit off because the image has a huge white border as you can see in the following image (I applied img { border:1px solid orange } for clarification):
