Trying to prevent a custom checkbox from jumping when checked

I was making some custom radio and checkboxes for a project scheduled for next week and I thought maybe something a little different like an "X" instead of a check. To make this question short and simple:

Question:

• When this custom checkbox is checked, the check box jumps about 2px up. How do I prevent that behavior?

Possible Duplicate:

• Question: Why do these checkbox-hacked radio buttons jump when they are selected?

• Differences: OP's CSS is a convoluted mess of body nth-of-type selectors and the only answer is unaccepted with a convoluted mess of CSS without an explanation of how it works.

Thank you for your time.

http://ift.tt/1RJCOmE